fix(nacos): call unsubscribe when watching is stopped

[shenqidebaozi]

Description (what this PR does / why we need it):

Which issue(s) this PR fixes (resolves / be part of):

fixes #

Other special notes for reviewer:

[codecov-commenter]

Codecov Report

Merging #1697 (2bc9858) into main (7aa9f35) will decrease coverage by 0.05%.
The diff coverage is n/a.

❗ Current head 2bc9858 differs from pull request most recent head 95546bd. Consider uploading reports for the commit 95546bd to get more accurate results

@@            Coverage Diff             @@
##             main    #1697      +/-   ##
==========================================
- Coverage   81.17%   81.11%   -0.06%     
==========================================
  Files          78       78              
  Lines        3431     3431              
==========================================
- Hits         2785     2783       -2     
- Misses        443      445       +2     
  Partials      203      203              

Impacted Files	Coverage Δ
internal/context/context.go	97.01% <0.00%> (-2.99%)	⬇️

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