[gdb/testsuite, tclint] Fix syntax error in gdb.base/dtrace-probe.exp

[gdb/testsuite, tclint] Fix syntax error in gdb.base/dtrace-probe.exp

When running tclint with gdb.base/dtrace-probe.exp I get:
...
$ tclint gdb.base/dtrace-probe.exp
$exp:67:45: syntax error: expected newline or semicolon, got ]
...
due to these lines:
...
    67      runto "-probe-dtrace test:two-locations"]
    68      runto "-probe-dtrace test:two-locations"]
...

Fix this by dropping the trailing ']'.

Tested by rerunning tclint.

Approved-By: Simon Marchi <simon.marchi@efficios.com>
PR testsuite/33403
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=33403