Revert "[Gradle][Tests][MPP] Introduce NEXT_RELEASE versions constant for Gradle and AGP"

This reverts commit 23a1598f0d.

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/testbase/TestVersions.kt

@@ -22,11 +22,10 @@ interface TestVersions {
         const val G_7_6 = "7.6"
         // https://gradle.org/nightly/
         // Retention policy is 3 months
-        const val G_8_0 = "8.0.2"
+        const val G_8_0 = "8.0-rc-1"
         const val MIN_SUPPORTED = minSupportedGradleVersion
         const val MIN_SUPPORTED_KPM = G_7_0
         const val MAX_SUPPORTED = G_7_6
-        const val NEXT_RELEASE = G_8_0
     }
 
     object Kotlin {
@@ -48,7 +47,6 @@ interface TestVersions {
 
         const val MIN_SUPPORTED = AGP_42 // KotlinAndroidPlugin.minimalSupportedAgpVersion
         const val MAX_SUPPORTED = AGP_74 // Update once Gradle MAX_SUPPORTED version will be bumped
-        const val NEXT_RELEASE = AGP_80
     }
 
     enum class AgpCompatibilityMatrix(