Deprecate support for Gaia v5 in favor of Gaia v7

[seanchen1991]

Closes: #1986

Description

Per the acceptance criteria listed in #1986:

• Remove legacy option from the chain-upgrade CLI
• Remove all the references to gaia-v4 and upgrade the CI test suite to use gaia-v7

---

PR author checklist:

• Added changelog entry, using unclog.
• Added tests: integration (for Hermes) or unit/mock tests (for modules).
• Linked to GitHub issue.
• Updated code comments and documentation (e.g., docs/).

Reviewer checklist:

• Reviewed Files changed in the GitHub PR explorer.
• Manually tested (in case integration/unit/mock tests are absent).

[romac]

Shouldn't the test-end-to-end-current-gaia be updated to Gaia v6 and test-end-to-end-future-gaia be updated to v7?

We should probably also remove the v5 integration-test.

[adizere]

Shouldn't the test-end-to-end-current-gaia be updated to Gaia v6 and test-end-to-end-future-gaia be updated to v7?

This makes sense. Alternatively, with Sean we discussed the following scheme:

• Current → rename to Legacy (should be Vega, v6)
• Future → rename to Current (now is Theta, v7)
• Ref: Ecosystem dependencies tracking for Hermes development #2030

Using the scheme "legacy/current" is more appropriate than "current/future" because v7 is already live. We will rarely be ahead of the release cycle (hence no need for "future").

[romac]

Sounds good!

[seanchen1991]

I ran into an issue when running the build-ibc-chains.sh script on OSX. The

RUN apk add --no-cache $PACKAGES && make tools && make install

step seems quite brittle. @andynog also ran the script on Fedora and encountered an issue on the same step.

@soareschen suggested that perhaps building the new Gaia versions can be made less error-prone by using nix shell in the gaia.Dockerfile.

[adizere]

Thanks Sean & Mikhail!