Update ports used in HA docs

[kgolubic]

From internal Slack channel:

One port to rule them all, but should be consistent in docs.

There are configuration flags on page for High availability, but when we describing Env flags
the config is not the same as it is used in docker parameters in previous paragraph,
and that is confusing

Data and Coordinator instances paragraphs

export MEMGRAPH_BOLT_PORT=7692

There is 7692 port specified, but should be 7687 (to be consistent on this page.
https://memgraph.com/docs/clustering/high-availability

[katarinasupe]

@as51340, next time you update HA docs, can you take a look at this and make sure all ports used on the page are correct? I don't want to get into this rabbit hole now, and I think it will be easier if you update it on the fly.