roachtest: cluster_creation failed

roachtest.cluster_creation [failed](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_RoachtestNightlyAwsBazel/20548015?buildTab=log) with [artifacts](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_RoachtestNightlyAwsBazel/20548015?buildTab=artifacts#/kv95/enc=false/nodes=3/cpu=96) on release-25.2.7-rc @ [6af1c9cf419e9a0667e39d129f9df8a4e0521374](https://github.com/cockroachdb/cockroach/commits/6af1c9cf419e9a0667e39d129f9df8a4e0521374):

```
test kv95/enc=false/nodes=3/cpu=96 failed: (test_runner.go:840).func4: in provider: aws: failed to run: aws ec2 run-instances --associate-public-ip-address --count 1 --instance-type c6a.24xlarge --image-id ami-0e83be366243f524a --key-name teamcity-runner-vjXO9PczcRCDA0smF35wcZLw068= --region us-east-2 --security-group-ids sg-04d72b57e29d671f1 --subnet-id subnet-0258dc9d1b6473d84 --tag-specifications ResourceType=instance,Tags=[{Key=usage,Value=roachtest},{Key=roachtest-branch,Value=release-25-2-7-rc},{Key=Cluster,Value=teamcity-20548015-1759383683-31-n4cpu96},{Key=spot,Value=true},{Key=roachprod,Value=true},{Key=cluster,Value=teamcity-20548015-1759383683-31-n4cpu96},{Key=lifetime,Value=12h0m0s},{Key=arch,Value=amd64},{Key=created,Value=2025-10-02T06:17:02Z},{Key=Name,Value=teamcity-20548015-1759383683-31-n4cpu96-0001}] ResourceType=volume,Tags=[{Key=usage,Value=roachtest},{Key=roachtest-branch,Value=release-25-2-7-rc},{Key=Cluster,Value=teamcity-20548015-1759383683-31-n4cpu96},{Key=spot,Value=true},{Key=roachprod,Value=true},{Key=cluster,Value=teamcity-20548015-1759383683-31-n4cpu96},{Key=lifetime,Value=12h0m0s},{Key=arch,Value=amd64},{Key=created,Value=2025-10-02T06:17:02Z},{Key=Name,Value=teamcity-20548015-1759383683-31-n4cpu96-0001}] --user-data file:///tmp/aws-startup-script1000262330 --iam-instance-profile Name=roachprod-testing --block-device-mapping file:///tmp/aws-block-device-mapping2956416181 --instance-market-options MarketType=spot,SpotOptions={SpotInstanceType=one-time,InstanceInterruptionBehavior=terminate} --output json: stderr:
An error occurred (InsufficientInstanceCapacity) when calling the RunInstances operation (reached max retries: 2): We currently do not have sufficient c6a.24xlarge capacity in the Availability Zone you requested (us-east-2a). Our system will be working on provisioning additional capacity. You can currently get c6a.24xlarge capacity by not specifying an Availability Zone in your request or choosing us-east-2b, us-east-2c.: exit status 254 [owner=test-eng]
```

Parameters:
- cloud=aws
- coverageBuild=false
- cpu=96
- runtimeAssertionsBuild=false
- ssd=0
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)

Same failure on other branches

- #154604 roachtest: cluster_creation failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-25.3.3-rc]
- #154600 roachtest: cluster_creation failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-24.3.21-rc]
- #154240 roachtest: cluster_creation failed [O-roachtest O-robot T-testeng X-infra-flake branch-master]
- #154109 roachtest: cluster_creation failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-25.4]
- #153766 roachtest: cluster_creation failed [O-roachtest O-robot T-testeng X-infra-flake branch-master]
- #153765 roachtest: cluster_creation failed [O-roachtest O-robot T-testeng X-infra-flake branch-master]
- #153764 roachtest: cluster_creation failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-25.3.2-rc]
- #153763 roachtest: cluster_creation failed [O-roachtest O-robot T-testeng X-infra-flake branch-master]
- #153563 roachtest: cluster_creation failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-25.3]
- #153562 roachtest: cluster_creation failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-25.3]

/cc @cockroachdb/test-eng

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

Jira issue: CRDB-55026