basalt-26.3.1-rc: roachtest: cluster_creation failed

roachtest.cluster_creation [failed](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_RoachtestNightlyAwsBazel/21484507?buildTab=log) with [artifacts](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_RoachtestNightlyAwsBazel/21484507?buildTab=artifacts#/kv0/enc=false/nodes=3/cpu=32/size=64kb/splt=100) on basalt-26.3.1-rc @ [63bc2c6772a94c6d763293cd0c2ec06e359c0a36](https://github.com/cockroachdb/cockroach/commits/63bc2c6772a94c6d763293cd0c2ec06e359c0a36):

```
test kv0/enc=false/nodes=3/cpu=32/size=64kb/splt=100 failed: (test_runner.go:1017).func4: in provider: aws: failed to create instance teamcity-21484507-1787724187-15-n4cpu32-0004: aws create failed due to capacity for machine type m6i.xlarge in zone(s) [us-east-2c]; suggested zone(s): [us-east-2a us-east-2b]: failed to run: aws ec2 run-instances --associate-public-ip-address --count 1 --instance-type m6i.xlarge --image-id ami-0e83be366243f524a --key-name teamcity-runner-Eqep2QYiGkcFpmLV5d44c-Tlxfk= --region us-east-2 --security-group-ids sg-04d72b57e29d671f1 --subnet-id subnet-0e71591c1fe06645e --tag-specifications ResourceType=instance,Tags=[{Key=usage,Value=roachtest},{Key=roachtest-branch,Value=basalt-26-3-1-rc},{Key=arch,Value=amd64},{Key=created,Value=2026-08-26T06:22:56Z},{Key=Cluster,Value=teamcity-21484507-1787724187-15-n4cpu32},{Key=spot,Value=true},{Key=roachprod,Value=true},{Key=cluster,Value=teamcity-21484507-1787724187-15-n4cpu32},{Key=lifetime,Value=12h0m0s},{Key=Name,Value=teamcity-21484507-1787724187-15-n4cpu32-0004},{Key=roachprod-data-disk,Value=boot}] ResourceType=volume,Tags=[{Key=usage,Value=roachtest},{Key=roachtest-branch,Value=basalt-26-3-1-rc},{Key=arch,Value=amd64},{Key=created,Value=2026-08-26T06:22:56Z},{Key=Cluster,Value=teamcity-21484507-1787724187-15-n4cpu32},{Key=spot,Value=true},{Key=roachprod,Value=true},{Key=cluster,Value=teamcity-21484507-1787724187-15-n4cpu32},{Key=lifetime,Value=12h0m0s},{Key=Name,Value=teamcity-21484507-1787724187-15-n4cpu32-0004},{Key=roachprod-data-disk,Value=boot}] --user-data file:///tmp/aws-startup-script2540531357 --iam-instance-profile Name=roachprod-testing --block-device-mapping file:///tmp/aws-block-device-mapping2212577764 --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 m6i.xlarge capacity in the Availability Zone you requested (us-east-2c). Our system will be working on provisioning additional capacity. You can currently get m6i.xlarge capacity by not specifying an Availability Zone in your request or choosing us-east-2a, us-east-2b.: exit status 254 [owner=test-eng]
```

Parameters:
- MetamorphicFilesystem=ext4
- MetamorphicVolumeType=io2
- cloud=aws
- coverageBuild=false
- cpu=32
- diskCount=0
- 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)

Same failure on other branches

- #173220 roachtest: cluster_creation failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-25.4.15-rc]
- #173219 roachtest: cluster_creation failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-25.2.23-rc]
- #173209 roachtest: cluster_creation failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-25.4.15-rc]
- #173187 roachtest: cluster_creation failed [O-roachtest O-robot T-testeng X-infra-flake branch-master]
- #173160 release-26.3.1-rc: roachtest: cluster_creation failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-26.3.1-rc]
- #173156 release-26.2.6-rc: roachtest: cluster_creation failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-26.2.6-rc]
- #173155 roachtest: cluster_creation failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-25.4.15-rc]
- #173154 roachtest: cluster_creation failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-25.2.23-rc]
- #172904 basalt-26.3: roachtest: cluster_creation failed [O-roachtest O-robot T-testeng X-infra-flake branch-basalt-26.3]
- #172635 release-26.2: roachtest: cluster_creation failed [O-roachtest O-robot T-testeng X-infra-flake branch-release-26.2]

/cc @cockroachlabs/test-eng

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Jira issue: CRDB-67192

Start with the roachtest README and test_runner.go around line 1017, then inspect the AWS cluster-creation path for the reported m6i.xlarge capacity failure in us-east-2c. Compare the repeated related issues and the TeamCity log to determine the intended handling; done means cluster_creation behaves as intended when AWS reports insufficient capacity.

Written by the indexing model from the issue text.