When Bro was compiled with broker disabled, then some Bro scripts
were referencing functions and types that were not defined. Fixed
by adding @ifdefs to several scripts. Removed one @ifdef because
it was causing several unit tests to fail.
Also fixed the @TEST-REQUIRES check in tests that rely on broker so
that such tests are skipped when broker is disabled.
Added tests for the table_clear and vector_clear BIFs, and added
more tests for container types (e.g. adding the same element twice
to a set or table, or overwriting a record field value, etc.).
Also reorganized several test cases.
Simplified some function names, fixed some names of broker script wrappers,
reorder some broker function calls to avoid potential race conditions, and
don't have bro read a trace file when it will not be used.
