Replace @RequiresFlagEnabled annotation from Telecom CTS tests when it is not supported.

Some Telecom CTS tests do not run JUnit4 and thus do not support the @RequiresFlagEnabled annotation. This CL replaces unsupported uses of that annotation with manual flag checks.

Test: these are test classes
Flag: EXEMPT TEST_ONLY
Bug: 437270484
Change-Id: I64ba3b29bd81b6704b442244c2a5088af8338e2f