regressions: Don't print misleading 'Expect error ...' lines.

regressions: Don't print misleading 'Expect error ...' lines.

Some tests in the regressions directory deliberately print
error messages.  As long as they still PASS, this is OK.

However these tests also printed some misleading messages
about what error to expect.  Since error messages were slightly
different across distros, these messages were not accurate.

Therefore remove these messages, and replace with a general
message before all tests telling users not to worry about
errors from the tests as long as the tests don't fail.

Cherry picked from commit e7ee6eebed6ee3a5b56c0482ba2770e697d8febc
and rebased for stable branch.