Remove supported environments with 7.20

[toco-cam]

Acceptance Criteria (Required on creation):

• The environments are removed from the docs
• Any CI or code that is needed only for these versions is removed or refactored

Environments to remove:

• Java 8
• Wildfly 14 / 15 / 16 / 17 / 18 / 19 / 20 / 21 / 22 / 24 / 25
• JBoss EAP 7.2 / 7.3
• PostgreSQL 12
• Amazon Aurora PostgreSQL 12
• Oracle 12
• Websphere 9
• Spring 4

Modules to retire:

• Standalone web applications
• RPA Bridge -> Remove from docs

Hand to the community:

• XQuery and Velocity script engines
• XSLT script engine

Breakdown

#### General
- [x] https://github.com/camunda/camunda-docs-static/pull/351
- [ ] https://github.com/camunda/camunda-docs-manual/pull/1495

Dependencies:

#### Java 8
- [ ] https://github.com/camunda/camunda-bpm-platform/issues/3488
- [x] Remove Java 8 references from the docs - none found
- [ ] https://github.com/camunda/camunda-bpm-platform/issues/3690

#### Spring 4
- [ ] https://github.com/camunda/camunda-bpm-platform/pull/3641

Servers:

#### WildFly

#### JBoss EAP
- [ ] https://github.com/camunda/camunda-bpm-platform/issues/3642

#### Websphere 9
- [ ] https://github.com/camunda/camunda-bpm-platform/issues/3607

Databases:

#### PostgreSQL 12
- [ ] https://github.com/camunda/camunda-bpm-platform/issues/3602

#### Amazon Aurora PostgreSQL 12
- [ ] https://github.com/camunda/camunda-bpm-platform/issues/3604

#### Oracle 12
- [ ] https://github.com/camunda/camunda-bpm-platform/issues/3597

Modules:

#### Standalone web applications
- [x] https://github.com/camunda/camunda-bpm-platform/issues/3429
- [ ] https://github.com/camunda/camunda-bpm-platform/issues/3479
- [ ] https://github.com/camunda/camunda-bpm-platform/issues/3582

#### RPA Bridge
- [ ] https://github.com/camunda/camunda-bpm-platform/issues/3606

#### XQuery and Velocity script engines
- [ ] https://github.com/camunda/camunda-bpm-platform/issues/3695
- [ ] https://github.com/camunda/camunda-bpm-platform/issues/3696

#### XSLT script engine
- [ ] https://github.com/camunda/camunda-bpm-platform/issues/3697

Hints (optional):

Links:

[mboskamp]

Unassigned me for now. The next DRI can take over and remove any left environments.