default helm vtgate maxReplicas to replicas

[gflarity]

Using the Unsharded keyspace example from:
https://github.com/vitessio/vitess/tree/master/helm/vitess

Fails:
Error: render error in "vitess/templates/vitess.yaml": template: vitess/templates/vitess.yaml:51:3: executing "vitess/templates/vitess.yaml" at <include "vtgate" (tu...>: error calling include: template: vitess/templates/_vtgate.tpl:141:6: executing "vtgate" at <gt .maxReplicas .rep...>: error calling gt: invalid type for comparison
On inspection it looks like .maxReplicas is undefined and so you can't compare it to an int. This fix assumes that maxReplicas isn't required, and defaults it to .replicas. Alternatively .maxReplicas could be required and the documentation should be updated instead.

Cheers,
Geoff

[enisoc]

@derekperkins Can you take a look at this if you have a chance?

[derekperkins]

Yep, I'll be dealing with this in the next day or two.

[gflarity]

Sorry, I didn't realize I need to git commit -s. I can close and reopen a signed version if my PR makes sense.

[enisoc]

@gflarity Not your fault. I think we switched to DCO after you opened this PR. :)

If you're comfortable with rebases, you could fix this PR without having to open a new one, with something like:

git rebase --signoff master
git push -f

[gflarity]

Done!

[sougou]

Now that I understand how helms work, I like this change :)

[derekperkins]

LGTM. Let's go ahead and merge it