Rename service_introspection_mode to introspection_mode

[mini-1235]

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Basic Info

Info	Please fill out this column
Ticket(s) this addresses	(add tickets here #1)
Primary OS tested on	(Ubuntu, MacOS, Windows)
Robotic platform tested on	(Steve's Robot, gazebo simulation of Tally, hardware turtlebot)
Does this PR contain AI generated software?	(No; Yes and it is marked inline in the code)

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Description of contribution in a few bullet points

Introspection mode now supports for both action and service, so rename it to introspection_mode to avoid ambiguity

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
• Check that any significant change is added to the migration guide
• Check that any new features OR changes to existing behaviors are reflected in the tuning guide
• Check that any new functions have Doxygen added
• Check that any new features have test coverage
• Check that any new plugins is added to the plugins page
• If BT Node, Additionally: add to BT's XML index of nodes for groot, BT package's readme table, and BT library lists
• Should this be backported to current distributions? If so, tag with backport-*.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Files with missing lines	Coverage Δ
..._ros_common/include/nav2_ros_common/node_utils.hpp	90.47% <100.00%> (ø)
nav2_smac_planner/src/smac_planner_2d.cpp	93.30% <100.00%> (ø)
nav2_smac_planner/src/smac_planner_hybrid.cpp	87.13% <100.00%> (ø)

... and 4 files with indirect coverage changes

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