[FIR] Fixed phase for FirCompanionGenerationProcessor to COMPANION_GENERATION

Phase COMPILER_REQUIRED_ANNOTATIONS causes errors in the kotlinx serialization tests:

org.jetbrains.kotlin.fir.symbols.FirLazyResolveContractViolationException: `lazyResolveToPhase(COMPILER_REQUIRED_ANNOTATIONS)` cannot be called from a transformer with a phase COMPILER_REQUIRED_ANNOTATIONS.
`lazyResolveToPhase` can be called only from a transformer with a phase which is strictly greater than a requested phase;
 i.e., `lazyResolveToPhase(A)` may be only called from a lazy transformer with a phase B, where A < B. This is a contract of lazy resolve

plugins/kotlinx-serialization/testData/diagnostics/externalSerialierJava.kt

@@ -1,4 +1,3 @@
-// FIR_DISABLE_LAZY_RESOLVE_CHECKS
 // FIR_IDENTICAL
 // WITH_STDLIB
 // SKIP_TXT