release-26.3: roachtest: follower-reads/mixed-version/single-region failed

roachtest.follower-reads/mixed-version/single-region [failed](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_Roachtests_RoachtestNightlyGcePrivateBazel/21492055?buildTab=log) with [artifacts](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_Roachtests_RoachtestNightlyGcePrivateBazel/21492055?buildTab=artifacts#/follower-reads/mixed-version/single-region) on release-26.3 @ [2388f34e6ec51df924f33c2e6231de4a3e9cd2f8](https://github.com/cockroachdb/cockroach/commits/2388f34e6ec51df924f33c2e6231de4a3e9cd2f8):

Failed with:

```
(follower_reads.go:390).runFollowerReadsTest: failed to get follower read counts: Get "https://10.91.97.131:26258/_status/vars": EOF
(mixedversion.go:926).Run: panic (stack trace above): t.Fatal() was called
test artifacts and logs in: /artifacts/follower-reads/mixed-version/single-region/cpu_arch=arm64/run_1
```
Cluster Node to Ip Mapping:
| Node | Public IP | Private IP |
| --- | --- | --- |
| teamcity-21492055-1788154532-72-n4cpu2-0001 | | 10.91.97.138 |
| teamcity-21492055-1788154532-72-n4cpu2-0002 | | 10.91.97.4 |
| teamcity-21492055-1788154532-72-n4cpu2-0003 | | 10.91.97.137 |
| teamcity-21492055-1788154532-72-n4cpu2-0004 | | 10.91.97.131 |

Parameters:
- arch=arm64
- cloud=gce
- coverageBuild=false
- cpu=2
- diskCount=0
- encrypted=false
- fs=ext4
- localSSD=false
- mvtDeploymentMode=shared-process
- mvtVersions=v25.2.15 → v25.4.1 → v26.2.3 → v26.3.2-dev-2388f34e6ec51df924f33c2e6231de4a3e9cd2f8 (release-26.3)
- 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-21492055/follower-reads-mixed-version-single-region/1788172042097/1788172676753)

See: [Datadog Logs](https://us5.datadoghq.com/logs?query=service%3Aroachtest+%40cluster%3Ateamcity-21492055-1788154532-72-n4cpu2&from_ts=1788172042097&to_ts=1788172676753&live=false&storage=flex_tier)

/cc @cockroachlabs/kv-triage

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

Jira issue: CRDB-67679