Fix detekt unused import in DefaultAuthCredentialsServiceTest for 2025.3

Remove unused spyk import.

Author: aseemxs

plugins/amazonq/shared/jetbrains-community/tst/software/aws/toolkits/jetbrains/services/amazonq/lsp/auth/DefaultAuthCredentialsServiceTest.kt

@@ -15,7 +15,6 @@ import io.mockk.just
 import io.mockk.mockk
 import io.mockk.mockkStatic
 import io.mockk.runs
-import io.mockk.spyk
 import io.mockk.verify
 import kotlinx.coroutines.test.advanceUntilIdle
 import kotlinx.coroutines.test.runTest