Make all CIs running in ubuntu latest.

[wu-sheng]

• If this pull request closes/resolves/fixes an existing issue, replace the issue number. Closes #.
• Update the CHANGES log.

According to the current CI status,

The ubuntu-16.04 environment is deprecated and will be removed on September 20, 2021. Migrate to ubuntu-latest instead. For more details see actions/runner-images#3287

I bump up all Ubuntu versions consistently, to avoid unexpected cases.

[codecov]

Codecov Report

Merging #7021 (4c8dacb) into master (03294b8) will decrease coverage by 4.88%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #7021      +/-   ##
============================================
- Coverage     53.67%   48.79%   -4.89%     
+ Complexity     4280     3771     -509     
============================================
  Files          1863     1866       +3     
  Lines         40273    40336      +63     
  Branches       4496     4468      -28     
============================================
- Hits          21618    19683    -1935     
- Misses        17604    19630    +2026     
+ Partials       1051     1023      -28     

Impacted Files	Coverage Δ
...skywalking/oap/server/core/alarm/AlarmMessage.java	0.00% <0.00%> (-100.00%)	⬇️
...ng/oap/server/core/analysis/config/NoneStream.java	0.00% <0.00%> (-100.00%)	⬇️
...log/analyzer/provider/log/ILogAnalyzerService.java	0.00% <0.00%> (-100.00%)	⬇️
...ement/ui/template/UITemplateManagementService.java	0.00% <0.00%> (-100.00%)	⬇️
.../parser/listener/DatabaseSlowStatementBuilder.java	0.00% <0.00%> (-100.00%)	⬇️
...r/agent/kafka/provider/handler/JsonLogHandler.java	0.00% <0.00%> (-100.00%)	⬇️
.../receiver/zabbix/provider/config/ZabbixConfig.java	0.00% <0.00%> (-100.00%)	⬇️
...in/elasticsearch/base/TimeRangeIndexNameMaker.java	0.00% <0.00%> (-100.00%)	⬇️
...bix/provider/protocol/ZabbixProtocolDataCodec.java	0.00% <0.00%> (-100.00%)	⬇️
...eceiver/zabbix/provider/protocol/ZabbixServer.java	0.00% <0.00%> (-92.00%)	⬇️
... and 160 more

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