tests/check/elements/: consistent pad (de)activation

tests/check/elements/: consistent pad (de)activation

Original commit message from CVS:
* tests/check/elements/mpeg2enc.c: (setup_mpeg2enc),
(cleanup_mpeg2enc):
* tests/check/elements/rganalysis.c: (cleanup_rganalysis):
* tests/check/elements/wavpackdec.c: (setup_wavpackdec),
(cleanup_wavpackdec):
* tests/check/elements/wavpackenc.c: (setup_wavpackenc),
(cleanup_wavpackenc):
* tests/check/elements/y4menc.c: (setup_y4menc), (cleanup_y4menc):
consistent pad (de)activation