scripts: twisterlib: filter coverage information

When dumping logs from the `--inline-logs` option, remove any coverage
information that may be contained in those logs. Coverage dumps are
unrelated to any test failures and make it harder to find the failing
test information. In extreme cases the relevant information is lost due
to terminal scrollback limits.

If the raw dump information is required, it is still present in the
original `handler.log` file.

Signed-off-by: Jordan Yates <jordan@embeint.com>