SELinux changes for I/O tracing.

See also go/perfetto-io-tracing-security.

* Grant CAP_DAC_READ_SEARCH to traced_probes.
* Allow traced_probes to list selected labels.
* Change ext4 and f2fs events to be available on user builds.

Bug: 74584014
Cherry-picked from aosp/631805
Change-Id: I891a0209be981d760a828a69e4831e238248ebad
Merged-In: I891a0209be981d760a828a69e4831e238248ebad