Fix a large amount of minor fixes to maintainer scripts and other done
downstream in the official Debian packaging.

Changes include:

https://salsa.debian.org/mariadb-team/mariadb-server/-/commit/38198d0b9e1c7821ddd074e308b25034bdcdce5b
> Limit check of running mysqld/mariadbd to system users (Closes: #1032047)
>
> If a random user has their own copy of mysqld/mariadbd running, the
> dpkg maintainer script should not care about it.

https://salsa.debian.org/mariadb-team/mariadb-server/-/commit/8116354d22e0b8eade6d8f0594c57300d5d5cff5
> Make error more helpful in case server restart fails (Related: #1033234)
>
> Bugs such as https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1033234
> and https://bugs.launchpad.net/ubuntu/+source/mariadb-10.6/+bug/2011293
> show that currently dpkg stopping on service stop/start does not have
> a very helpful error message.

https://salsa.debian.org/mariadb-team/mariadb-server/-/commit/8675e97202171812a1afdb438a17cb29a99836fb
> Complement upstream commits with more complete mysql->mariadb conversion
>
> The upstream commit 952af4a1 missed some places where 'mysql' or
> 'MySQL' can and should be converted to use 'mariadb' or 'MariaDB'.

https://salsa.debian.org/mariadb-team/mariadb-server/-/commit/c98361330063e7dccbf8d21aa20e48179ba5c1e4
> Fix indentation in Debian post and pre scripts
>
> There is several misindentation inside Debian post and pre
> installation scripts. False indentation with space as indent space
> should be 2 and indentation with tabs.
>
> Adopt upstream commit 7cbb45d1 in Debian by conserving customizations
> in:
> - debian/mariadb-server.postinst
> - debian/mariadb-server.postrm
> - debian/mariadb-server.preinst

https://salsa.debian.org/mariadb-team/mariadb-server/-/commit/d0bcab443fa6d44084dc674ba29b79516c6239ba
> Ensure spaces are used everywhere instead of tabs for indentation

https://salsa.debian.org/mariadb-team/mariadb-server/-/commit/0300a9157cc69f75e01ac9c0d6e033d8be661492
> Complement previous upstream commits to fix Shellcheck issues
>
> - Unify if/then and while/do on separate lines
> - Fix indentation to be consistent
> - Use "$()" instead of backticks for subshells
> - Exit code cannot be -1, must be 0-255
> - Remove unused variables MYCHECK and MYCHECK_PARAMS
> - Rewrite messy command-line database calls to an easier to read form
>   that does exactly the same
> - Use 'command -v' test instead of 'which'
>
> With this commit, all of debian/* is Shellcheck clean.

Also
* Update mariadb.conf.d template to tell users where to create logdir
  if they are not using journald
* Remove use of work 'slave'
* Add minor workaround for Debian Bug #1022994 if TMPDIR is empty
* Make start/stop in maintainer scripts correctly check mariadbd
  ownership and only start/stop processes owned by root or 'mysql'
* Remove obsolete 'NO_UPDATE_BUILD_VERSION=1' as it did not affect the
  RocksDB build reproducibility as previously assumed
* Run 'wrap-and-sort -av'