build_{rust,dpkg}.sh - scripts rework fixes/simplifications

[interduo]

Some small improvements/bugfixes:

• merge mkdir in one command,
• use cat << EOF construction instead many echo'es,
• merge systemctl calls in one cmds,
• remove unneded loop,
• other minor things found when running ./bash -x build_rust.sh or ./bash -x build_dpkg.sh
  (doubled files, bad compare operator for strings)
• run python dependencies install instead only printing command,
• uninstall script remove services unit files,
• uninstall script mods: remove doubled clean/uninstall script,
• firstly stop then disable services when uninstalling,
• fix python lib alias after installing libreqos (postinst script) not in build_dpkg.sh script,
• add quiet mode to pip install,
• merge setting attrs for postinst postrm scripts
• supress popd cmd messages,
• fixes showing ip in motd,
• use one command instead of two when disabling/enabling with stop,

[thebracket]

Tagging this for beta 2. I'll try and get it merged locally and tested today. I generally prefer keeping build scripts an obvious "one step at a time", so I may break some things out again for clarity (the build script is something you run pretty infrequently if you aren't actively working on the back-end, so it's a pretty low priority)

[interduo]

For me lqos is mostly backend. I logged into GUI few times only. This means that its doing its work like a charm :)

[interduo]

ok - now I see nothing to improve/clean, waiting for review+squash&merge,

[interduo]

Now it looks much more professional without unneeded messages:

[interduo]

@thebracket did You checked this PR? It would be awesome if we could have this in beta2

[interduo]

@thebracket could we merging this now? it takes much minutes to resolve conflicts...

[interduo]

@thebracket when will You do review? This is resolving few problems whitch users were asking on chat in last week.

[interduo]

@thebracket what about merging this and bugfix #550 and release new beta?

This is the state - I tested much on prod with very heavy load.