bugfix: solve NoSuchMethodError when the version of druid used < 1.1.3

[ggndnn]

Ⅰ. Describe what this PR did

Use seata's StringUtils, instead of druid's.

Ⅱ. Does this pull request fix one issue?

fix #1606

Ⅲ. Why don't you add test cases (unit test/integration test)?

Ⅳ. Describe how to verify it

Ⅴ. Special notes for reviews

[zjinlei]

LGTM

[codecov-io]

Codecov Report

Merging #1607 into develop will decrease coverage by <.01%.
The diff coverage is 0%.

@@              Coverage Diff              @@
##             develop    #1607      +/-   ##
=============================================
- Coverage      46.45%   46.44%   -0.01%     
  Complexity      1713     1713              
=============================================
  Files            350      350              
  Lines          12827    12827              
  Branches        1615     1615              
=============================================
- Hits            5959     5958       -1     
  Misses          6222     6222              
- Partials         646      647       +1

Impacted Files	Coverage Δ	Complexity Δ
...rm/datasource/sql/struct/TableMetaCacheOracle.java	0% <0%> (ø)	0 <0> (ø)	⬇️
...seata/rm/datasource/sql/struct/TableMetaCache.java	55.69% <0%> (ø)	14 <1> (ø)	⬇️
...server/store/file/FileTransactionStoreManager.java	47.03% <0%> (-0.35%)	19% <0%> (ø)

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[xingfudeshi]

LGTM.