fix(module:statistic): correct DOM structure and naming

[HyperLife1119]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/NG-ZORRO/ng-zorro-antd/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• Application (the showcase website) / infrastructure changes
• Other... Please describe:

What is the current behavior?

Issue Number: N/A

What is the new behavior?

• 

• Rename NzStatisticNumber to NzStatisticContentValue.

Does this PR introduce a breaking change?

• Yes
• No

Other information

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.08%. Comparing base (b0a4287) to head (cb35f39).
⚠️ Report is 24 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #9330      +/-   ##
==========================================
- Coverage   92.12%   92.08%   -0.05%     
==========================================
  Files         561      561              
  Lines       19631    19631              
  Branches     3107     3000     -107     
==========================================
- Hits        18086    18078       -8     
- Misses       1206     1214       +8     
  Partials      339      339              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[Nicoss54]

LGTM

[Nicoss54]

@HyperLife1119 WDYT to create a little schematics for this breaking change?

[HyperLife1119]

@HyperLife1119 WDYT to create a little schematics for this breaking change?

Are you interested in this? This component is only used internally, although it exports a public API.

[Laffery]

LGTM

[Nicoss54]

Are you interested in this? This component is only used internally, although it exports a public API.

for the futur, i could help on it :), as this component is only for internal use maybe it's not necessary to create a schematics only for an internal use