Remove hard-coded policy version from secilc step

This change makes init's SELinux policy compilation step target the
highest SELinux policy language version supported by the kernel.
Prior to this change the version was simply hard-coded in init.

P. S. clang-format (part of presubmit for this change) is being
counter-productive trying to format the section with secilc
parameters. The resulting layout is harder to read. This commit thus
disables clang-format for this section of code and formats the code
for improved readability.

Test: Remove precompiled policy, device boots up, no new denials.
      Added log statement to print out the policy version passed
      into secilc -- it printed 30, as expected.
Bug: 31363362

Change-Id: I151017b5211712861bafb662525e794a44026dd2