release-26.2: roachtest: follower-reads/mixed-version/survival=region/locality=global/reads=strong failed

**Note:** This build has runtime assertions enabled. If the same failure was hit in a run without assertions enabled, there should be a similar failure without this message. If there isn't one, then this failure is likely due to an assertion violation or (assertion) timeout.

roachtest.follower-reads/mixed-version/survival=region/locality=global/reads=strong [failed](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_Roachtests_RoachtestNightlyGcePrivateBazel/21495748?buildTab=log) with [artifacts](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_Roachtests_RoachtestNightlyGcePrivateBazel/21495748?buildTab=artifacts#/follower-reads/mixed-version/survival=region/locality=global/reads=strong) on release-26.2 @ [2f80fb3f27825ed762cb7160a3fbac936dc47b49](https://github.com/cockroachdb/cockroach/commits/2f80fb3f27825ed762cb7160a3fbac936dc47b49):

Failed with:

```
(follower_reads.go:903).verifyHighFollowerReadRatios: too many intervals with more than 2 nodes with low follower read ratios: 5 intervals > 4 threshold. Bad intervals:
interval 15:53:30-15:53:40: n1 ratio: 0.000 n2 ratio: 1.000 n3 ratio: 0.000 n4 ratio: 0.898 n5 ratio: 1.000 n6 ratio: 1.000
interval 15:53:40-15:53:50: n1 ratio: 0.000 n2 ratio: 1.000 n3 ratio: 0.000 n4 ratio: 0.682 n5 ratio: 1.000 n6 ratio: 1.000
interval 15:53:50-15:54:00: n1 ratio: 0.000 n2 ratio: 1.000 n3 ratio: 0.001 n4 ratio: 0.730 n5 ratio: 1.000 n6 ratio: 1.000
interval 15:54:00-15:54:10: n1 ratio: 0.001 n2 ratio: 1.000 n3 ratio: 0.000 n4 ratio: 0.686 n5 ratio: 0.989 n6 ratio: 1.000
interval 15:54:10-15:54:20: n1 ratio: 0.001 n2 ratio: 0.988 n3 ratio: 0.000 n4 ratio: 0.805 n5 ratio: 1.005 n6 ratio: 0.983
(mixedversion.go:926).Run: panic (stack trace above): t.Fatal() was called
test artifacts and logs in: /artifacts/follower-reads/mixed-version/survival=region/locality=global/reads=strong/run_1
```
Cluster Node to Ip Mapping:
| Node | Public IP | Private IP |
| --- | --- | --- |
| teamcity-21495748-1788328393-216-n6cpu4-geo-0001 | | 10.91.96.160 |
| teamcity-21495748-1788328393-216-n6cpu4-geo-0002 | | 10.91.96.223 |
| teamcity-21495748-1788328393-216-n6cpu4-geo-0003 | | 10.91.96.229 |
| teamcity-21495748-1788328393-216-n6cpu4-geo-0004 | | 10.91.128.123 |
| teamcity-21495748-1788328393-216-n6cpu4-geo-0005 | | 10.91.128.124 |
| teamcity-21495748-1788328393-216-n6cpu4-geo-0006 | | 10.91.48.4 |

Parameters:
- arch=amd64
- cloud=gce
- coverageBuild=false
- cpu=4
- diskCount=0
- encrypted=false
- fs=ext4
- localSSD=true
- mvtDeploymentMode=system-only
- mvtVersions=v26.1.1 → v26.2.7-dev-2f80fb3f27825ed762cb7160a3fbac936dc47b49 (release-26.2)
- runtimeAssertionsBuild=true
Help

See: [roachtest README](https://github.com/cockroachdb/cockroach/blob/master/pkg/cmd/roachtest/README.md)

See: [How To Investigate \(internal\)](https://cockroachlabs.atlassian.net/l/c/SSSBr8c7)

See: [Grafana](https://go.crdb.dev/roachtest-grafana/teamcity-21495748/follower-reads-mixed-version-survival-region-locality-global-re/1788362337274/1788365040591)

Same failure on other branches

- #174107 roachtest: follower-reads/mixed-version/survival=region/locality=global/reads=strong failed [C-test-failure O-roachtest O-robot T-kv branch-master release-blocker]
- #173417 release-26.3: roachtest: follower-reads/mixed-version/survival=region/locality=global/reads=strong failed [A-testing B-runtime-assertions-enabled C-bug C-test-failure O-roachtest O-robot P-3 T-kv branch-release-26.3]

/cc @cockroachlabs/kv-triage

[This test on roachdash](https://roachdash.crdb.dev/?filter=status:open%20t:.*follower-reads/mixed-version/survival=region/locality=global/reads=strong.*&sort=title+created&display=lastcommented+project) | [Improve this report!](https://github.com/cockroachdb/cockroach/tree/master/pkg/cmd/bazci/githubpost/issues)

Jira issue: CRDB-67817