fix(adasvc): fix getting attachment issues for triple

[justxuewei]

What this PR does:

• fix getting attachment issue for triple

Which issue(s) this PR fixes:
Fixes #

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[codecov-commenter]

Codecov Report

Merging #1811 (2578157) into 3.0 (e00cf8d) will increase coverage by 0.06%.
The diff coverage is 66.66%.

❗ Current head 2578157 differs from pull request most recent head 8ead2da. Consider uploading reports for the commit 8ead2da to get more accurate results

@@            Coverage Diff             @@
##              3.0    #1811      +/-   ##
==========================================
+ Coverage   47.62%   47.69%   +0.06%     
==========================================
  Files         262      262              
  Lines       15115    15103      -12     
==========================================
+ Hits         7199     7203       +4     
+ Misses       7132     7115      -17     
- Partials      784      785       +1     

Impacted Files	Coverage Δ
protocol/invocation/rpcinvocation.go	16.54% <66.66%> (+2.57%)	⬆️
registry/nacos/listener.go	78.26% <0.00%> (-2.61%)	⬇️
metrics/prometheus/reporter.go	26.85% <0.00%> (-1.72%)	⬇️
remoting/nacos/builder.go	76.66% <0.00%> (+2.75%)	⬆️
metadata/report/delegate/delegate_report.go	34.43% <0.00%> (+7.94%)	⬆️

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[Mulavar]

这部分重复的代码需不需要包装成一个方法

[justxuewei]

这个地方我权衡过，主要 attachment 格式没有显式规定（比如数组里是否只能有一个元素之类的），所以我考虑是说先单独写。