[appd] fix: gRPC web address default flag value

[fdymylja]

Description

The grpc-web address flag was using the grpc address flag default value instead of its own, this was causing address binding conflicts.

This PR fixes this.

On a secondary note, it appears that disabling grpc-web via flags is ignored (or overridden).

closes: #XXXX

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[robert-zaremba]

Pre approving. Don't forget about changelog update.

[robert-zaremba]

@alessio , @fdymylja - should we backport this to release/0.40.x as well? if yes then don't forget to add tag and create a new PR as this will be merged.

[fdymylja]

@alessio , @fdymylja - should we backport this to release/0.40.x as well? if yes then don't forget to add tag and create a new PR as this will be merged.

I think we should. Also it appears that the grpc-web.enable flag is being ignored.