gdb/testsuite/gdb.base/break.exp: split test_break_default

gdb/testsuite/gdb.base/break.exp: split test_break_default

One special thing here is that the part just above this one, that sets
catchpoints and verifies they are not hit, requires that we resume
execution to verify that the catchpoints are indeed not hit.   I guess
it was previously achieved by the until command, but it doesn't happen
now that the until is moved into test_break_default.  Add a
gdb_continue_to_end after setting the catchpoints.  If any catchpoint
were to be hit, it would catch the problem.

Change-Id: I5d4b43da91886b1beda9f6e56b05aa04331a9c05
Approved-By: Kevin Buettner <kevinb@redhat.com>