Move boringssl self tests from early-init to init.

In previous releases, these self tests had a secondary purpose
of writing a flag file to save future processes from running
some slow self checks.  This is no longer true in T.

However running the tests from early-init has caused issues
on some devices as the kernel's entropy pool is not yet
initialised, causing the process to block for a second or more.

Bug: 231946889
Test: m && flashall
Change-Id: I2116f2029ca6a21e4359407dfff4dc79edd39084