Change logLevel to not touch simple-logger defaultLogLevel

[gabrielfeo]

Fix #331

Config.logLevel / DEVELOCITY_API_LOG_LEVEL internally changes org.slf4j.simpleLogger.defaultLogLevel, which changes level of all loggers, not only the library's as the javadoc says. In practice, this is an issue when the user is using simple-logger and using loggers (or using other dependencies that use loggers), as changing Config.logLevel / DEVELOCITY_API_LOG_LEVEL will unexpectedly affect those loggers.

[github-actions]

Job Summary for Gradle

Check PR :: kotlin-tests

Gradle Root Project	Requested Tasks	Gradle Version	Build Outcome	Build Scan®
develocity-api-kotlin	test compileIntegrationTestKotlin :build-logic:check :libra…	8.12	❌