Latched map subscriber QoS depth 1

[doisyg]

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Basic Info

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Ticket(s) this addresses	(add tickets here #1)
Primary OS tested on	Ubuntu
Robotic platform tested on	Deoxry robot
Does this PR contain AI generated software?	No
Was this PR description generated by AI software?	No

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Description of contribution in a few bullet points

Change the depth of the map and costmap related subscribers from 10 (default) to 1 (explicitly through the constructor nav2::qos::LatchedSubscriptionQoS(1)). This matches the depth of the latched publishers (default depth of 1).
This is needed for us in the context of using huge maps + Zenoh SHM in order to not have to set ZENOH_SHM_ALLOC_SIZE to the size of the message * [10 (the depth of the subscriber) + 2 (recommended margin)] and optimizing RAM usage.
This works well for our setup (all comms are local). Though a point to discuss is if this could cause issues for receiving map/costmap over wireless / lossy connections. But since we are only touching latched topics (and matching the publishers), I am not sure it is really an issue.
An alternative would be to have the user override the QoS of these subscribers.

(side change: use nav2::qos for test_map_saver_cli and test_map_saver_publisher)

Description of documentation updates required from your changes

Description of how this change was tested

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Future work that may be required in bullet points

For Maintainers:

• Check that any new parameters added are updated in docs.nav2.org
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