[Build] Migrate most of the build logic from Project.buildDir usage

It's going to be deprecated in Gradle 8.3

There's currently no way to pass a `org.gradle.api.provider.Provider` to the JavaExec.systemProperty or Test.systemProperty. There's a workaround using `org.gradle.process.CommandLineArgumentProvider`, but I intentionally don't rework these calls as Gradle is going to allow passing providers to configure system properties: https://github.com/gradle/gradle/issues/12247#issuecomment-1568427242
^KTI-1473 In Progress

libraries/tools/kotlin-gradle-plugin-integration-tests/build.gradle.kts

@@ -126,7 +126,7 @@ val cleanTestKitCacheTask = tasks.register<Delete>("cleanTestKitCache") {
     group = "Build"
     description = "Deletes temporary Gradle TestKit cache"
 
-    delete(project.buildDir.resolve("testKitCache"))
+    delete(layout.buildDirectory.dir("testKitCache"))
 }
 
 tasks.register<Delete>("cleanUserHomeKonanDir") {

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/commonize-kt-56729-consume-library-with-two-roots/consumer/build.gradle.kts

@@ -7,7 +7,7 @@ plugins {
 }
 
 repositories {
-    maven(project(":producer").buildDir.resolve("repo"))
+    maven(project(":producer").layout.buildDirectory.dir("repo"))
     mavenLocal()
     mavenCentral()
 }