init.rc: Move /system/bin/boringssl_self_test{32,64} call to early-init.

This should ensure that the self tests run before any other binaries
that load libcrypto and which would otherwise run into SELinux denials
trying to create the marker file /dev/boringssl/selftest/[hash]

The invocation of the self test binaries from the Conscrypt apex
requires the apex to be mounted so it remains at a later point in
the boot process.

Bug: 137267623
Test: Treehugger
Change-Id: I34266d6e9d2f394fffa8a2c7725479b5770d119c