Also adopt Salsa-CI to test for buster-backports.

Package uses debhelper 12 but that is available in both Debian Buster,
so no changes needed.

- Remove copyright reference to directory no longer in Galera 4
- Update to Debian Policy version 4.5.0

Update to upstream version '26.4.5'
with Debian dir 94891662d1484dd4ce9b7be4edefaa14b7879139

Fix systemd unit and start script.

See merge request mariadb-team/galera-4!2

The start script does not work on Debian because the path for config
file is not correct.
The environment definition in the systemd unit file is redundant (and
problematic on Debian) with config file definition in the bash start
script (garb-systemd).
Also, the bash script needed some linting IMO.
Finally, Alias should not be used in systemd unit file and static
symlink should be deployed at postinstall instead.
See https://wiki.debian.org/Teams/pkg-systemd/Packaging#systemd_unit_files_naming_and_installation

Satisfies Lintian notice:
https://lintian.debian.org/tags/rules-requires-root-missing.html

Verified with 'hardening-check -v /usr/bin/garbd'.

Before:
/usr/bin/garbd:
 Position Independent Executable: yes
 Stack protected: yes
 Fortify Source functions: yes (some protected functions found)
	unprotected: memmove
	unprotected: snprintf
	unprotected: memcpy
	unprotected: strncpy
	unprotected: strncat
	unprotected: poll
	unprotected: memset
	unprotected: strcpy
	protected: sprintf
	protected: snprintf
	protected: memcpy
	protected: fprintf
	protected: vsnprintf
	protected: syslog
	protected: strcat
 Read-only relocations: yes
 Immediate binding: no, not found!
 Stack clash protection: unknown, no -fstack-clash-protection instructions found
 Control flow integrity: unknown, no -fcf-protection instructions found!

After:
/usr/bin/garbd:
 Position Independent Executable: yes
 Stack protected: yes
 Fortify Source functions: yes (some protected functions found)
	unprotected: strncpy
	unprotected: poll
	unprotected: memset
	unprotected: strcpy
	unprotected: strncat
	unprotected: memmove
	unprotected: snprintf
	unprotected: memcpy
	protected: syslog
	protected: strcat
	protected: snprintf
	protected: memcpy
	protected: vsnprintf
	protected: fprintf
	protected: sprintf
 Read-only relocations: yes
 Immediate binding: yes
 Stack clash protection: unknown, no -fstack-clash-protection instructions found
 Control flow integrity: unknown, no -fcf-protection instructions found!

Lintian no longer complains about this, on the contrary Lintian states
that it is now unused.

Copied from Salsa-CI source at
https://salsa.debian.org/salsa-ci-team/pipeline/blob/master/salsa-ci.yml

See also
https://salsa.debian.org/salsa-ci-team/pipeline/tree/master#enabling-the-pipeline-for-tags

Update to upstream version '26.4.3'
with Debian dir d0b868d5d5dd9cf6b44f95bb32a2fc985df3ef00

Fix some issues reported by lintian

See merge request mariadb-team/galera-3!5

Fixes lintian: field-name-typo-dep5-copyright
See https://lintian.debian.org/tags/field-name-typo-dep5-copyright.html for more details.

+ debian/rules: Call dh_missing rather than using dh_install --list-missing.

Fixes lintian: package-uses-old-debhelper-compat-version
See https://lintian.debian.org/tags/package-uses-old-debhelper-compat-version.html for more details.

Fixes lintian: out-of-date-standards-version
See https://lintian.debian.org/tags/out-of-date-standards-version.html for more details.

Fixes lintian: debian-watch-uses-insecure-uri
See https://lintian.debian.org/tags/debian-watch-uses-insecure-uri.html for more details.