xds/internal/xdsclient/xdsresource: Preallocate VirtualHost slice correctly

[alingse]

when I want to add feature for linter makezero in PR ashanbrown/makezero#15 , I run a github action for real world repos, and the action result report this bug.

RELEASE NOTES: N/A

[aranjans]

@alingse Thanks for writing in. While this change is functional, it's generally considered more efficient in Go to set an initial length of 0 and a capacity when using make with slices that will be appended to. This change looks good to me but we need to make sure there are no other place we are using the same as above.
@arvindbr8 Pitching you in to have a review from your side as well. This LGTM!

[alingse]

@aranjans I have run makezero linter for this project, and found only this bug. you can run it locally.

[arvindbr8]

makezero is not a stylecheck we run on CI in this repo. We could consider this change if we decide to add this as part of our other stylechecks

[alingse]

It's not a style ok? It's a stupid bug @arvindbr8 have you ever really check this? @aranjans

the vhs have already pre-alloc with len(config.VirtualHosts) size, and then append it again.

if the VirtualHosts has three items, finally the vhs will be []VirtualHostWithInterceptors{ zeroValue, zeroValue,zeroValue , v1, v2, v3}

[zasweq]

LGTM

[arvindbr8]

In the first pass, I didnt realize this was a bug fix from the PR description. This looks good to me. Thanks for catching this.

[alingse]

In the first pass, I didnt realize this was a bug fix from the PR description. This looks good to me. Thanks for catching this.

sorry for the lack of detailed description in the PR. I took the lazy way out and directly copied the description from another PR. 😿