fix: fee currency change

[mrq1911]

fee currency should not change when account holds native currency already

related to the #454

[github-actions]

Crate versions that have not been updated:

• runtime-integration-tests: v0.3.6
• pallet-exchange: v5.3.7
• pallet-exchange-benchmarking: v3.3.16
• pallet-lbp: v4.4.6
• pallet-xyk: v4.0.3
• basilisk-runtime: v63.0.0
• common-runtime: v1.10.0
• testing-basilisk-runtime: v63.0.0

Runtime version has not been increased.

[codecov]

Codecov Report

Merging #514 (c835c74) into master (e0d2161) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #514   +/-   ##
=======================================
  Coverage   81.21%   81.21%           
=======================================
  Files          19       19           
  Lines        1927     1927           
=======================================
  Hits         1565     1565           
  Misses        362      362           

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