Regression test T13438 is no longer marked as "expect_broken" in the testsuite driver.

Closes #13438 (closed)

The problem in the issue above has already been fixed (probably by @adamgundry) , but the regression test was still marked as "expect_broken" in the testsuite. I have removed the ghci invocation of the :ctags command in the test, since that command was not mentioned in the original issue #13438 (closed), and the :ctags feature will be removed soon (see: #19884 (closed))

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