[JVM] Micro-optimize method signature mapping

This commit optimizes functions related to method signature mapping on
the JVM backend. The most significant change is avoiding re-allocations
in StringBuilder when building internal names. The commit also includes
minor optimizations, such as removing redundant allocations of strings
and other objects.

core/descriptors.jvm/src/org/jetbrains/kotlin/load/kotlin/methodSignatureMapping.kt

@@ -93,7 +93,7 @@ internal fun CallableDescriptor.computeJvmSignature(): String? = signatures {
 internal val ClassDescriptor.internalName: String
     get() {
         JavaToKotlinClassMap.mapKotlinToJava(fqNameSafe.toUnsafe())?.let {
-            return JvmClassName.byClassId(it).internalName
+            return JvmClassName.internalNameByClassId(it)
         }
 
         return computeInternalName(this)