Temporary: make "Pre-release classes were found in dependencies" warning

See KT-66551

compiler/cli/src/org/jetbrains/kotlin/cli/common/messages/AnalyzerWithCompilerReport.kt

@@ -206,7 +206,7 @@ class AnalyzerWithCompilerReport(
 
             if (hasPrereleaseClasses) {
                 messageCollector.report(
-                    ERROR,
+                    WARNING,
                     "Pre-release classes were found in dependencies. " +
                             "Remove them from the classpath, recompile with a release compiler " +
                             "or use '-Xskip-prerelease-check' to suppress errors"

compiler/testData/compileKotlinAgainstCustomBinaries/releaseCompilerAgainstPreReleaseLibrary/output.fir.txt

@@ -1,4 +1,3 @@
-error: pre-release classes were found in dependencies. Remove them from the classpath, recompile with a release compiler or use '-Xskip-prerelease-check' to suppress errors
 compiler/testData/compileKotlinAgainstCustomBinaries/releaseCompilerAgainstPreReleaseLibrary/source.kt:8:28: error: unresolved reference 'method'.
     val methodCall = param.method()
                            ^^^^^^

compiler/testData/compileKotlinAgainstCustomBinaries/releaseCompilerAgainstPreReleaseLibrary/output.txt

@@ -1,4 +1,3 @@
-error: pre-release classes were found in dependencies. Remove them from the classpath, recompile with a release compiler or use '-Xskip-prerelease-check' to suppress errors
 compiler/testData/compileKotlinAgainstCustomBinaries/releaseCompilerAgainstPreReleaseLibrary/source.kt:8:28: error: unresolved reference: method
     val methodCall = param.method()
                            ^^^^^^

compiler/testData/compileKotlinAgainstCustomBinaries/releaseCompilerAgainstPreReleaseLibraryJs/output.fir.txt

@@ -1,4 +1,3 @@
-error: pre-release classes were found in dependencies. Remove them from the classpath, recompile with a release compiler or use '-Xskip-prerelease-check' to suppress errors
 compiler/testData/compileKotlinAgainstCustomBinaries/releaseCompilerAgainstPreReleaseLibraryJs/source.kt:8:28: error: unresolved reference 'method'.
     val methodCall = param.method()
                            ^^^^^^

compiler/testData/compileKotlinAgainstCustomBinaries/releaseCompilerAgainstPreReleaseLibraryJs/output.txt

@@ -1,4 +1,3 @@
-error: pre-release classes were found in dependencies. Remove them from the classpath, recompile with a release compiler or use '-Xskip-prerelease-check' to suppress errors
 compiler/testData/compileKotlinAgainstCustomBinaries/releaseCompilerAgainstPreReleaseLibraryJs/source.kt:8:28: error: unresolved reference: method
     val methodCall = param.method()
                            ^^^^^^