Update DDEV config to support v1.25.0 (Debian Trixie)

[mneudert]

Description

The recent DDEV 1.25.0 release switch from Debian Bookworm to Debian Trixie.

In our base setup there are some packages that prevent starting with the new base image:

• longer available: gconf-service, libgconf-2-4
• renamed: libgdk-pixbuf2.0-0 => libgdk-pixbuf-2.0-0
• unused: libappindicator1

From some limited tests they seem to be safe to remove (or rename) for both a 1.24.10 base image, and the newer Trixie release.

Local switch can be done by pinning a base image:

# .ddev/config.local.yaml
webimage: ddev/ddev-webserver:v1.24.10
webimage: ddev/ddev-webserver:v1.25.0

And should then be visible in the PHPUnit runtime banner:

Runtime:       PHP 7.2.34-55+0~20250707.109+debian12~1.gbp140deb
Runtime:       PHP 7.2.34-59+0~20251218.111+debian13~1.gbp637f71

Only did some baseline tests with some PHPUnit and some UI tests. Both versions seemed to work just fine with the updated package list.

Checklist

• [NA] I have understood, reviewed, and tested all AI outputs before use
• [NA] All AI instructions respect security, IP, and privacy rules

Review

• Functional review done
• Potential edge cases thought about (behaviour of the code with strange input, with strange internal state or possible interactions with other Matomo subsystems)
• Usability review done (is anything maybe unclear or think about anything that would cause people to reach out to support)
• Security review done
• Wording review done
• Code review done
• Tests were added if useful/possible
• Reviewed for breaking changes
• Developer changelog updated if needed
• New documentation added or existing documentation updated