Change LockMode from MEMORY to DB when the StoreMode is DB

[zhangthen]

Ⅰ. Describe what this PR did

If the StoreMode is 'DB' and the LockMode is 'MEMORY', the locks in 'MEMORY' cann't be released normally after the transaction commit or rollback.

Ⅱ. Does this pull request fix one issue?

Change LockMode from MEMORY to DB automatically when the StoreMode is DB .

[codecov-io]

Codecov Report

Merging #1145 into develop will decrease coverage by 0.01%.
The diff coverage is 33.33%.

@@              Coverage Diff              @@
##             develop    #1145      +/-   ##
=============================================
- Coverage       41.9%   41.88%   -0.02%     
  Complexity      1372     1372              
=============================================
  Files            245      245              
  Lines          10188    10194       +6     
  Branches        1332     1334       +2     
=============================================
+ Hits            4269     4270       +1     
- Misses          5364     5367       +3     
- Partials         555      557       +2

Impacted Files	Coverage Δ	Complexity Δ
.../main/java/io/seata/server/lock/LockerFactory.java	37.03% <33.33%> (-1.06%)	3 <2> (ø)
...server/store/file/FileTransactionStoreManager.java	45.64% <0%> (-0.35%)	19% <0%> (ø)

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[slievrly]

if startup in file mode and use db lock ，can it work?

[leizhiyuan]

can we remove the settings of lock mode, only one setting: "storeMode"?