Each dpkg -i call produces ~8 lines of verbose output per package
(Selecting, Reading database, Preparing, Unpacking, Setting up). For a
hub build with ~20 dependencies this adds ~160 lines of noise to the
Jenkins logs. Wrap the dpkg call with run_and_print_on_failure so output
is only shown when installation fails. Also remove -x from shebang to
suppress shell trace output.

Ticket: ENT-12619
Signed-off-by: Lars Erik Wik <[email protected]>
Co-Authored-By: Claude Opus 4.6 <[email protected]>

Cleanup commands in prepare-testmachine-chroot (fuser, umount) may fail
when there is nothing to kill or unmount, producing confusing error
output in Jenkins logs. Redirect their output to /dev/null, matching the
pattern already used in test-on-testmachine lines 94 and 96.

Also suppress stdout/stderr from ps|grep process checks in
test-on-testmachine that look for known benign processes (minilogd,
gpg-agent). We only care about the exit code, not the output, so use
grep -q and redirect ps stderr.

Ticket: ENT-12619
Signed-off-by: Lars Erik Wik <[email protected]>
Co-Authored-By: Claude Opus 4.6 <[email protected]>

The function already suppresses command output on success but shows
lines matching Warning/Error. This caused ~350 lines of known-benign
output per build from automake subdir-objects warnings and libtool
install warnings. Filter these out so only actionable warnings are
shown.

Ticket: ENT-12619
Signed-off-by: Lars Erik Wik <[email protected]>
Co-Authored-By: Claude Opus 4.6 <[email protected]>

The 'Description' field for cfbuild-nghttp2-devel was misspelled as
'Desciption', causing dpkg to emit a 'missing Description field' warning
on every subsequent dpkg -i call (~10+ times per testing-pr build).

Ticket: ENT-12619
Signed-off-by: Lars Erik Wik <[email protected]>
Co-Authored-By: Claude Opus 4.6 <[email protected]>

The -u option enables unified diff which makes it look a little nicer.
It uses +/- instead of </>. However, -u is not supported on HP-UX which
causes the following output to be printed instead:

```
21:28:47 ==================== Current environment ========================
21:28:47 diff: illegal option -- u
21:28:47 	usage: diff [ -C n ] [ -S name ] [ -bcefhilnrstw ] dir1 dir2
21:28:47 		diff [-C n ] [ -bcefhintw ] file1 file2
21:28:47 		diff [ -D string ] [ -biw ] file1 file2
21:28:47 =================================================================
```

I also changed the output to only be printed if there is an actual
change in the environment. This way, we won't print the environment
every time this script is sourced.

Ticket: ENT-12619
Signed-off-by: Lars Erik Wik <[email protected]>

This script is sourced many times and causes a lot of noise. All these
log messages are redunant, in that the same information is printed in
the end of the file.

Ticket: ENT-12619
Signed-off-by: Lars Erik Wik <[email protected]>

Ticket: ENT-12619
Signed-off-by: Lars Erik Wik <[email protected]>

Signed-off-by: Lars Erik Wik <[email protected]>