Fixed crash in bt_service_node when the service is not available in time (backport #5606)

[mergify]

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Basic Info

Info	Please fill out this column
Ticket(s) this addresses	none
Primary OS tested on	to be honest, I haven't tested this.
Robotic platform tested on	untested
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

• This fixes a crash in the bt_service_node that triggers when a service is not ready in time.
• The problem is just a silly mistake that inadvertently calls constructor 4 on this page: https://en.cppreference.com/w/cpp/string/basic_string/basic_string.html

Description of how this change was tested

• To be honest, it wasn't tested. However, I saw this crash on the jazzy branch and noticed the bug is still present on main. Rather than open an issue, I figured I'd just throw up this trivial patch.

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-*.

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This is an automatic backport of pull request #5606 done by [Mergify](https://mergify.com).

[mergify]

@mergify[bot], all pull requests must be targeted towards the main development branch.
Once merged into main, it is possible to backport to @jazzy, but it must be in main
to have these changes reflected into new distributions.