The `-r` option does not filter out fixtures

[vkarak]

Here is how to reproduce:

Listing works fine:

$ ./bin/reframe -C unittests/resources/settings.py -c unittests/resources/checks_unlisted/fixtures_simple.py -n Hello -l

[List of matched checks]
- HelloTest /2b3e4546
Found 1 check(s)

But running runs also the irrelevant HelloFixture:

$ ./bin/reframe -C unittests/resources/settings.py -c unittests/resources/checks_unlisted/fixtures_simple.py -n Hello -r

[==========] Running 3 check(s)
[==========] Started on Wed Oct 19 22:43:20 2022

[----------] start processing checks
[ RUN      ] HelloTest /2b3e4546 @generic:default+builtin
[ RUN      ] HelloTest ~generic /98821229 @generic:default+builtin
[ RUN      ] HelloFixture ~generic /93cd42f0 @generic:default+builtin
[       OK ] (1/3) HelloTest /2b3e4546 @generic:default+builtin
[       OK ] (2/3) HelloTest ~generic /98821229 @generic:default+builtin
[       OK ] (3/3) HelloFixture ~generic /93cd42f0 @generic:default+builtin
[----------] all spawned checks have finished

[  PASSED  ] Ran 3/3 test case(s) from 3 check(s) (0 failure(s), 0 skipped)
[==========] Finished on Wed Oct 19 22:43:21 2022

Similarly the concretised listing is not consistent. It lists one test case, but it reports 3 (as many as it ran):

$ ./bin/reframe -C unittests/resources/settings.py -c unittests/resources/checks_unlisted/fixtures_simple.py -n Hello -lC

[List of matched checks]
- HelloTest /2b3e4546 @generic:default+builtin
Concretized 3 test case(s)