[AIRFLOW-XXXX] Remove unused local variable value

[kaxil]

tags = [] is unused as tag is defined again 2 lines down

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Issue link: Document only change, no JIRA issue

Make sure to mark the boxes below before creating PR: [x]

• Description above provides context of the change
• Commit message/PR title starts with [AIRFLOW-NNNN]. AIRFLOW-NNNN = JIRA ID^*
• Unit tests coverage for changes (not needed for documentation changes)
• Commits follow "How to write a good git commit message"
• Relevant documentation is updated including usage instructions.
• I will engage committers as explained in Contribution Workflow Example.

^* For document-only changes commit message can start with [AIRFLOW-XXXX].

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In case of fundamental code change, Airflow Improvement Proposal (AIP) is needed.
In case of a new dependency, check compliance with the ASF 3rd Party License Policy.
In case of backwards incompatible changes please leave a note in UPDATING.md.
Read the Pull Request Guidelines for more information.

[codecov-io]

Codecov Report

Merging #7496 into master will increase coverage by 0.11%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #7496      +/-   ##
==========================================
+ Coverage    86.5%   86.62%   +0.11%     
==========================================
  Files         887      887              
  Lines       41976    41975       -1     
==========================================
+ Hits        36312    36360      +48     
+ Misses       5664     5615      -49

Impacted Files	Coverage Δ
airflow/www/views.py	76.35% <ø> (+0.11%)	⬆️
...w/providers/apache/hive/operators/mysql_to_hive.py	35.84% <0%> (-64.16%)	⬇️
airflow/security/kerberos.py	30.43% <0%> (-45.66%)	⬇️
airflow/providers/mysql/operators/mysql.py	55% <0%> (-45%)	⬇️
airflow/providers/apache/hive/hooks/hive.py	76.02% <0%> (-1.54%)	⬇️
airflow/hooks/dbapi_hook.py	90.9% <0%> (-0.83%)	⬇️
airflow/jobs/backfill_job.py	91.83% <0%> (-0.29%)	⬇️
airflow/jobs/scheduler_job.py	90.09% <0%> (-0.15%)	⬇️
airflow/models/dag.py	91.29% <0%> (ø)	⬆️
... and 6 more

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