tests: remove pipelining tests

Remove the tests 530, 584, 1900, 1901, 1902, 1903 and 2033. They were
previously disabled.

The Pipelining code was removed from curl in commit 2f44e94efb,
April 2019.

Closes #5921

tests/data/DISABLED

@@ -2,31 +2,24 @@
 # test cases are run by runtests.pl. Just add the plain test case numbers, one
 # per line.
 # Lines starting with '#' letters are treated as comments.
-594
-1209
-1211
-1316
-1512
-836
-882
-938
-# test 1801 causes problems on Mac OS X and github
-# https://github.com/curl/curl/issues/380
-1801
-# test 1510 causes problems on the CI on github
-# example: https://travis-ci.org/curl/curl/builds/81633600
-1510
-# Pipelining test that is causing false positives a little too often
-1903
-# fnmatch differences are just too common to make testing them sensible
-1307
-# Pipelining is deprecated
-530
-584
-1900
-1901
-1902
-2033
+#
 # Uses SRP to "a server not supporting it" but modern stunnel versions
 # will silently accept it and remain happy
 323
+#
+594
+836
+882
+938
+1209
+1211
+# fnmatch differences are just too common to make testing them sensible
+1307
+1316
+# test 1510 causes problems on the CI on github
+# example: https://travis-ci.org/curl/curl/builds/81633600
+1510
+1512
+# test 1801 causes problems on Mac OS X and github
+# https://github.com/curl/curl/issues/380
+1801