fix(test): enable REST API for the upgrade chain (TestChainUpgrade)

[bdchatham]

What

TestChainUpgrade (merged in #438) resolves the proposal ID and polls the upgrade state over the Cosmos gov REST API, which is off by default. The generic provisioning omitted the override, so port 1317 was connection-refused and resolveProposalID polled a dead endpoint to the deadline. Adds the configOverrides the major-upgrade scenario uses: api.rest.enable=true, tx_index.indexer=kv.

Why it missed #438

This fix landed in my working tree after the #438 branch was pushed (the live smoke surfaced the gap), so the smoke-proven binary had it but the merged commit did not. This restores parity between main and the version that passed live.

Test

Smoke-proven: this is exactly the change that made --- PASS: TestChainUpgrade (319s) on harbor with the real v6.5 image pair. go build/vet -tags integration + golangci-lint clean.

🤖 Generated with Claude Code

[cursor]

PR Summary

Low Risk
Test-only integration harness change; no production controller or runtime behavior modified.

Overview
TestChainUpgrade provisions its chain through networkSpec, which previously only set genesis overrides (short gov voting period) and omitted seid runtime config. The test resolves proposal IDs and polls gov/upgrade state over the Cosmos REST API, which is disabled by default, so REST on port 1317 was unreachable and resolveProposalID timed out.

This PR adds upgradeConfig (aligned with the major-upgrade scenario): api.rest.enable=true and tx_index.indexer=kv, and passes it as Config on sei.NetworkSpec for both initial provision and the post-upgrade image re-apply so the override is not dropped on bump.

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