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

roachtest.follower-reads/mixed-version/survival=region/locality=global/reads=strong [failed](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_Roachtests_RoachtestNightlyGcePrivateBazel/21487457?buildTab=log) with [artifacts](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_Roachtests_RoachtestNightlyGcePrivateBazel/21487457?buildTab=artifacts#/follower-reads/mixed-version/survival=region/locality=global/reads=strong) on master @ [61e8d82a116c6abe7d91e47e27b8cd874c60184f](https://github.com/cockroachdb/cockroach/commits/61e8d82a116c6abe7d91e47e27b8cd874c60184f):

Failed with:

```
(follower_reads.go:390).runFollowerReadsTest: failed to get follower read counts: Get "https://10.91.96.114:26258/_status/vars": EOF
(mixedversion.go:1026).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-21487457-1787810259-114-n6cpu4-geo-0001 | | 10.91.97.23 |
| teamcity-21487457-1787810259-114-n6cpu4-geo-0002 | | 10.91.96.195 |
| teamcity-21487457-1787810259-114-n6cpu4-geo-0003 | | 10.91.96.114 |
| teamcity-21487457-1787810259-114-n6cpu4-geo-0004 | | 10.91.128.27 |
| teamcity-21487457-1787810259-114-n6cpu4-geo-0005 | | 10.91.128.77 |
| teamcity-21487457-1787810259-114-n6cpu4-geo-0006 | | 10.91.48.20 |

Parameters:
- arch=amd64
- cloud=gce
- coverageBuild=false
- cpu=4
- diskCount=0
- encrypted=false
- fs=ext4
- localSSD=true
- mvtDeploymentMode=system-only
- mvtVersions=v25.4.1 → v26.1.5 → v26.2.0 → v26.4.0-alpha.00000000-dev-61e8d82a116c6abe7d91e47e27b8cd874c60184f (master)
- runtimeAssertionsBuild=false
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-21487457/follower-reads-mixed-version-survival-region-locality-global-re/1787828262274/1787829001900)

See: [Datadog Logs](https://us5.datadoghq.com/logs?query=service%3Aroachtest+%40cluster%3Ateamcity-21487457-1787810259-114-n6cpu4-geo&from_ts=1787828262274&to_ts=1787829001900&live=false&storage=flex_tier)

Same failure on other branches

- #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

[Improve this report!](https://github.com/cockroachdb/cockroach/tree/master/pkg/cmd/bazci/githubpost/issues)

Jira issue: CRDB-67407