Add android.security.flags-aconfig-java-export target

We need to reference one of the android.security flags in the Tethering
module. The export target was already introduced in ag/30468201, this
change adds it to AOSP as well.

Flag: android.security.Flags.certificateTransparencyConfiguration
Bug: 379988507
Test: atest NetworkSecurityUnitTests
Merged-In: I14209528f744b1a5a093ba2ea5a0e3cf5dfc20a2
Merged-In: I9e9c3402ed872bfbb1b6ebbafda2a760082bdfe9
Change-Id: I8a4664a4a668e19d849d714f3f34d49d278dc1ce