Daml Finance cleanup after release SDK 2.9.1

[markus-da]

Shows that the 2.9.0-rc2 works in the Daml Finance repo. Our tests pass and no changes were required to the Daml code. Replace sdk-version: 2.9.0-rc2 by sdk-version: 2.9.0 (when released) or sdk-version: 2.9.0-rc3 (if required).

Fixes https://github.com/digital-asset/daml-finance/issues/1224

[johan-da]

Clean up daml-finance main after release:

• [x] update SDK version to 2.9.1
• [x] update hashes
• [x] highlight that daml-finance version is independent of SDK version:

      # version is independent of the actual sdk-version. It is used to create an assembly artifact here
      # https://digitalasset.jfrog.io/ui/repos/tree/General/assembly/daml-finance which is referenced by
      # docs.daml.com (in the docs/<sdk-version>/version.json files). The purpose of having an independent
      # version number is to allow the release of new assembly versions without waiting for a new SDK
      # release. For each new SDK release, we increment the minor version of the assembly.
      version: 1.5.0

Due to a bug in 2.9.1 the CI failed, a fix will be released with 2.9.3. Next step: update SDK to 2.9.3 once released