roachprod: add aws AZ override for c6id.24xlarge

Since the bump to new instance types in GCE and AWS [1],
we are still experiencing occasional cluster creation
issues owing to "insufficient capacity". GCE quota has
already been bumped, with `asia-northeast1` being the
latest, and hopefully last.

The most recent cluster creation in AWS is owing to
"insufficient capacity" of `c6id.24xlarge` in us-east-2a.
As a workaround, we extend the existing zone override
to place `c6id.24xlarge` into us-east-2b, which
allegedly has sufficient capacity.

Note, the long-term fix is to rework how cluster creation
retry currently operates, by effectively trying other AZs.

[1] #104419

Epic: none
Fixes: #78601 (comment)

Release note: None

pkg/roachprod/vm/aws/aws.go

@@ -279,8 +279,9 @@ var defaultCreateZones = []string{
 // not specifying an Availability Zone in your request or choosing us-east-2b, us-east-2c."
 // N.B. we implicitly specify AZ to select an AMI in that zone, hence we fall back to instance-specific overrides.
 var overrideDefaultCreateZones = map[string][]string{
-	"c6id.4xlarge": {"us-east-2c", "us-west-2b", "eu-west-2b"},
-	"c6id.8xlarge": {"us-east-2c", "us-west-2b", "eu-west-2b"},
+	"c6id.4xlarge":  {"us-east-2c", "us-west-2b", "eu-west-2b"},
+	"c6id.8xlarge":  {"us-east-2c", "us-west-2b", "eu-west-2b"},
+	"c6id.24xlarge": {"us-east-2b", "us-west-2b", "eu-west-2b"},
 }
 
 type Tag struct {