chore: Setup logging only once

[bitsandfoxes]

Resolves getsentry/sentry-unity#2248

Super minor but I had an issue open on the Unity SDK about it: We don't need to warn about setting up debug logging in production twice, right? Only once when actually setting the logger should suffice?

Sentry: (Warning) Sentry option 'Debug' is set to true while Environment is production. Be aware this can cause performance degradation and is not advised. See https://docs.sentry.io/platforms/dotnet/configuration/diagnostic-logger for more information 
UnityEngine.DebugLogHandler:Internal_Log(LogType, LogOption, String, Object)
Sentry.Unity.UnityLogger:Log(SentryLevel, String, Exception, Object[])
Sentry.SentrySdk:InitHub(SentryOptions)
Sentry.SentrySdk:Init(SentryOptions)
Sentry.Unity.SentryUnitySdk:Init(SentryUnityOptions)
Sentry.Unity.SentrySdk:Init(SentryUnityOptions)

Sentry: (Debug) DSN read from options: https://[email protected]/huehuehue 
UnityEngine.DebugLogHandler:Internal_Log(LogType, LogOption, String, Object)
Sentry.Unity.UnityLogger:Log(SentryLevel, String, Exception, Object[])
Sentry.Internal.SettingLocator:GetDsn()
Sentry.SentrySdk:InitHub(SentryOptions)
Sentry.SentrySdk:Init(SentryOptions)
Sentry.Unity.SentryUnitySdk:Init(SentryUnityOptions)
Sentry.Unity.SentrySdk:Init(SentryUnityOptions)

Sentry: (Debug) Initializing Hub for Dsn: 'https://[email protected]/huehuehue'. 
UnityEngine.DebugLogHandler:Internal_Log(LogType, LogOption, String, Object)
Sentry.Unity.UnityLogger:Log(SentryLevel, String, Exception, Object[])
Sentry.Internal.Hub:.ctor(SentryOptions, ISentryClient, ISessionManager, ISystemClock, IInternalScopeManager, RandomValuesFactory, IReplaySession, ISampleRandHelper, BackpressureMonitor)
Sentry.SentrySdk:InitHub(SentryOptions)
Sentry.SentrySdk:Init(SentryOptions)
Sentry.Unity.SentryUnitySdk:Init(SentryUnityOptions)
Sentry.Unity.SentrySdk:Init(SentryUnityOptions)

Sentry: (Warning) Sentry option 'Debug' is set to true while Environment is production. Be aware this can cause performance degradation and is not advised. See https://docs.sentry.io/platforms/dotnet/configuration/diagnostic-logger for more information 
UnityEngine.DebugLogHandler:Internal_Log(LogType, LogOption, String, Object)
Sentry.Unity.UnityLogger:Log(SentryLevel, String, Exception, Object[])
Sentry.SentryClient:.ctor(SentryOptions, IBackgroundWorker, RandomValuesFactory, ISessionManager, BackpressureMonitor)
Sentry.Internal.Hub:.ctor(SentryOptions, ISentryClient, ISessionManager, ISystemClock, IInternalScopeManager, RandomValuesFactory, IReplaySession, ISampleRandHelper, BackpressureMonitor)
Sentry.SentrySdk:InitHub(SentryOptions)
Sentry.SentrySdk:Init(SentryOptions)
Sentry.Unity.SentryUnitySdk:Init(SentryUnityOptions)
Sentry.Unity.SentrySdk:Init(SentryUnityOptions)

#skip-changelog

[cursor]

Bug: Logging guard blocks setup when diag logger exists

The guard condition prevents SetupLogging() from executing when DiagnosticLogger is already set. This breaks the logic when Debug is false, as SetupLogging() is responsible for setting DiagnosticLogger to null in that case. A logger set elsewhere will persist even when debugging is disabled.

 

[Flash0ver]

The "Init" / "UseSentry" / "AddSentry" path to initialize the Hub ... which is the most common scenario ... remains unchanged ... as it should.
But this common scenario is logging the "Debug is true && DiagnosticLogger is not null" case twice ... see dotnet run Sentry.Samples.Console.Basic --configuration Release.

Initializing and managing a SentryClient, e.g. when utilizing multiple DSNs, is an advanced scenario.
For these advanced scenarios, we could argue that

If the user has set Debug = true and explicitly a DiagnosticLogger, we do not warn.
While still providing the fallback of creating a ConsoleDiagnosticLogger as well as emitting a warning for the case where the user set Debug = true but not a custom DiagnosticLogger.

[Flash0ver]

However ... we would change the behavior of:

• User creates SentryClient
• with Debug is false
• with custom DiagnosticLogger

where now the DiagnosticLogger is no longer set to null.

suggestion:
Let's change the code to only emit the warning from InitHub, but not from SentryClient,
while leaving the rest of the "SetupLogging" behavior for both cases unchanged.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
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Additional details and impacted files

@@             Coverage Diff             @@
##             version6    #4706   +/-   ##
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  Coverage            ?   73.23%           
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  Files               ?      480           
  Lines               ?    17423           
  Branches            ?     3437           
===========================================
  Hits                ?    12759           
  Misses              ?     3815           
  Partials            ?      849           

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