check-flagged-apis: simplify unit test dependencies

Replace the current unit test runner DeviceJUnit4ClassRunner with JUnit4
and replace the (larger) dependency tradefed with the (smaller)
dependency junit.

This has no impact other than minimizing the unit test static_libs.

Bug: 334870672
Test: atest --host check-flagged-apis-test
Change-Id: I0520ab0feeea5ea2ed15905136ba2647f86162cb

tools/check-flagged-apis/Android.bp

@@ -46,6 +46,6 @@ java_test_host {
         "src/com/android/checkflaggedapis/CheckFlaggedApisTest.kt",
     ],
     static_libs: [
-        "tradefed",
+        "junit",
     ],
 }

tools/check-flagged-apis/src/com/android/checkflaggedapis/CheckFlaggedApisTest.kt

@@ -16,14 +16,13 @@
 package com.android.checkflaggedapis
 
 import android.aconfig.Aconfig
-import com.android.tradefed.testtype.DeviceJUnit4ClassRunner
-import com.android.tradefed.testtype.junit4.BaseHostJUnit4Test
 import java.io.ByteArrayInputStream
 import java.io.ByteArrayOutputStream
 import java.io.InputStream
 import org.junit.Assert.assertEquals
 import org.junit.Test
 import org.junit.runner.RunWith
+import org.junit.runners.JUnit4
 
 private val API_SIGNATURE =
     """
@@ -64,8 +63,8 @@ private fun generateFlagsProto(fooState: Aconfig.flag_state): InputStream {
   return ByteArrayInputStream(binaryProto.toByteArray())
 }
 
-@RunWith(DeviceJUnit4ClassRunner::class)
-class CheckFlaggedApisTest : BaseHostJUnit4Test() {
+@RunWith(JUnit4::class)
+class CheckFlaggedApisTest {
   @Test
   fun testParseApiSignature() {
     val expected = setOf(Pair(Symbol("android.Clazz.FOO"), Flag("android.flag.foo")))