Revert "Add maxTargetSdk restriction to unused APIs."

This reverts commit bc9a809f.

Reason for revert: Droidcop-triggered revert due to breakage https://android-build.googleplex.com/builds/quarterdeck?testMethod=testAppZygotePreload&testClass=android.app.cts.ServiceTest&atpConfigName=suite%2Ftest-mapping-presubmit-retry_cloud-tf&testModule=CtsAppTestCases&fkbb=6936597&lkbb=6936969&lkgb=6936551&testResults=true&branch=git_master&target=cf_x86_phone-userdebug>, bug b/171886397

Bug: 171886397
Change-Id: Ibe0f0430a3451477c1ee8ef56a596e91ea1e7672