Stopping tedge-mapper-c8y does not stop the FsWatcher actor gracefully

[PradeepKiruvale]

Describe the bug
When tedge-mapper-c8y is stopped using ^c or using systemctl it does not stop the FsWacher actor gracefully

To Reproduce

1. Install thin-edge.io
2. tedge connect c8y
3. wait for a while, Stop mapper sudo systemctl stop tedge-mapper-c8y
4. Observe logs sudo systemctl status tedge-mapper-c8y
   Observe there is an error log

ERROR Runtime: Actor FsWatcher-6 has finished unsuccessfully: ChannelE>

Expected behavior
Stopping mapper must stop all the actors properly/gracefully.

Screenshots
○ tedge-mapper-c8y.service - tedge-mapper-c8y converts Thin Edge JSON measurements to Cumulocity JSON format.
Loaded: loaded (/lib/systemd/system/tedge-mapper-c8y.service; enabled; vendor preset: enabled)
Active: inactive (dead) since Tue 2023-05-16 10:24:07 IST; 5s ago
Process: 161123 ExecStart=/usr/bin/tedge-mapper c8y (code=exited, status=0/SUCCESS)
Main PID: 161123 (code=exited, status=0/SUCCESS)
CPU: 192ms

May 16 10:24:07 ubuntu tedge-mapper[161123]: 2023-05-16T04:54:07.44217156Z INFO Runtime: Actor has finished: C8Y-REST-5
May 16 10:24:07 ubuntu tedge-mapper[161123]: 2023-05-16T04:54:07.44222366Z INFO Runtime: Actor has finished: Timer-7
May 16 10:24:07 ubuntu tedge-mapper[161123]: 2023-05-16T04:54:07.442280461Z INFO Runtime: Actor has finished: HTTP-4
May 16 10:24:07 ubuntu tedge-mapper[161123]: 2023-05-16T04:54:07.442344261Z ERROR Runtime: Actor FsWatcher-6 has finished unsuccessfully: ChannelE>
May 16 10:24:07 ubuntu tedge-mapper[161123]: 2023-05-16T04:54:07.442401861Z INFO Runtime: Actor has finished: HealthMonitorActor-1
May 16 10:24:07 ubuntu tedge-mapper[161123]: 2023-05-16T04:54:07.442734662Z INFO Runtime: Actor has finished: CumulocityMapper-8
May 16 10:24:07 ubuntu tedge-mapper[161123]: 2023-05-16T04:54:07.443021964Z INFO Runtime: Actor has finished: Signal-Handler-0
May 16 10:24:07 ubuntu tedge-mapper[161123]: 2023-05-16T04:54:07.443083764Z INFO Runtime: All actors have finished
May 16 10:24:07 ubuntu systemd[1]: tedge-mapper-c8y.service: Deactivated successfully.
May 16 10:24:07 ubuntu systemd[1]: Stopped tedge-mapper-c8y converts Thin Edge JSON measurements to Cumulocity JSON format..

Environment (please complete the following information):

• OS [incl. version]: Ubuntu
• Hardware [incl. revision] X64
• System-Architecture [e.g. result of "uname -a"]
• thin-edge.io version [e.g. 0.1.0] 0.10.0

Additional context

[albinsuresh]

Closed by #1984

To verify the fix, just follow the instructions in the ticket and make sure that the reported error log messages are not appearing when the mapper is stopped.

[gligorisaev]

QA has thoroughly checked the feature and here are the results:

• Test for ticket exists in the test suite.
• QA has tested the bug and could not reproduce it anymore.