test-utils: bump up debug_level when running under "make check"
test-utils: bump up debug_level when running under "make check"

Since automake's "make check" rule now logs the output of tests to a
log file, we might as well use maximum debugging, so that if something
fails, we have plenty of explanation why.

(We still parallelize parallelizable tests by default though, meaning
the output is not especially useful for those ones.)

Distrotech/libsoup,Distrotech/libsoup,Distrotech/libsoup,Distrotech/libsoup,Distrotech/libsoup