Fix mapping char_filter when mapping a hashtag (#7591)

[nathanmyles]

Signed-off-by: Nathan Myles myles.n.a@gmail.com

Issue: #7308 (cherry picked from commit e049338)

[nathanmyles]

Backports: #7591

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/17929/
• CommitID: 61556de

[kartg]

Tests with failures:
 - org.opensearch.cluster.routing.MovePrimaryFirstTests.testClusterGreenAfterPartialRelocation
 - org.opensearch.cluster.routing.MovePrimaryFirstTests.classMethod

This has cropped up in a some other 1.x backports - #8124 (comment)

It seems related to an old flaky test (#1957). A fix for this seems to have merged in - #2265 - but the test remains flaky on this branch. I'll refire Gradle check.

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: UNSTABLE ✅
• URL: https://build.ci.opensearch.org/job/gradle-check/17940/
• CommitID: 61556de

[codecov]

Codecov Report

Merging #8147 (61556de) into 1.x (a191f3d) will decrease coverage by 0.02%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##                1.x    #8147      +/-   ##
============================================
- Coverage     77.62%   77.61%   -0.02%     
+ Complexity    58808    58783      -25     
============================================
  Files          4223     4223              
  Lines        253545   253547       +2     
  Branches      38714    38714              
============================================
- Hits         196818   196786      -32     
- Misses        40715    40771      +56     
+ Partials      16012    15990      -22     

Impacted Files	Coverage Δ
...arch/analysis/common/MappingCharFilterFactory.java	50.00% <100.00%> (ø)
...n/java/org/opensearch/index/analysis/Analysis.java	84.89% <100.00%> (+0.22%)	⬆️

... and 449 files with indirect coverage changes