Rename/remove some compileKotlinAgainstCustomBinaries tests

"oldJvm*" tests are no longer testing the old JVM backend, so remove
that prefix from them. Also, remove the test "firAgainstOldJvm" because
it is now checking something that cannot NOT work.

compiler/testData/compileKotlinAgainstCustomBinaries/againstFir/library/a.kt

@@ -0,0 +1,5 @@
+package lib
+
+class Box(val value: String)
+
+inline fun <T> get(block: () -> T): T = block()

compiler/testData/compileKotlinAgainstCustomBinaries/againstFir/output.txt

@@ -0,0 +1,8 @@
+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/againstFir/source.kt:4:5: error: class 'lib.AKt' is compiled by a pre-release version of Kotlin and cannot be loaded by this version of the compiler
+    get { Box("OK").value }
+    ^
+compiler/testData/compileKotlinAgainstCustomBinaries/againstFir/source.kt:4:11: error: class 'lib.Box' is compiled by a pre-release version of Kotlin and cannot be loaded by this version of the compiler
+    get { Box("OK").value }
+          ^
+COMPILATION_ERROR

compiler/testData/compileKotlinAgainstCustomBinaries/againstFir/source.kt

@@ -0,0 +1,5 @@
+import lib.*
+
+fun main() {
+    get { Box("OK").value }
+}