[flutter_tools] Adds tests of mdns analytics events

[zanderso]

Description

Tests for #41384

Breaking Change

Does your PR require Flutter developers to manually update their apps to accommodate your change?

• Yes, this is a breaking change (Please read [Handling breaking changes]). Replace this with a link to the e-mail where you asked for input on this proposed change.
• No, this is not a breaking change.

[christopherfujino]

lgtm

[codecov]

Codecov Report

Merging #41410 into master will decrease coverage by 0.68%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #41410      +/-   ##
==========================================
- Coverage   60.43%   59.75%   -0.69%     
==========================================
  Files         193      193              
  Lines       18760    18760              
==========================================
- Hits        11338    11210     -128     
- Misses       7422     7550     +128

Flag	Coverage Δ
#flutter_tool	59.75% <ø> (-0.69%)	⬇️

Impacted Files	Coverage Δ
packages/flutter_tools/lib/src/base/net.dart	0% <0%> (-86.96%)	⬇️
...s/flutter_tools/lib/src/macos/xcode_validator.dart	0% <0%> (-85.72%)	⬇️
...s/flutter_tools/lib/src/tester/flutter_tester.dart	28.12% <0%> (-43.75%)	⬇️
packages/flutter_tools/lib/src/bundle.dart	47.82% <0%> (-31.53%)	⬇️
packages/flutter_tools/lib/src/base/common.dart	72.72% <0%> (-18.19%)	⬇️
packages/flutter_tools/lib/src/base/context.dart	49.12% <0%> (-8.78%)	⬇️
...ages/flutter_tools/lib/src/base/user_messages.dart	45.94% <0%> (-5.41%)	⬇️
packages/flutter_tools/lib/src/base/io.dart	48.88% <0%> (-4.45%)	⬇️
packages/flutter_tools/lib/src/base/terminal.dart	77.77% <0%> (-3.71%)	⬇️
packages/flutter_tools/lib/src/version.dart	91.9% <0%> (-1.43%)	⬇️
... and 5 more

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[tvolkert]

LGTM. Thanks.

[zanderso]

Coverage report isn't quite right for PRs that only have tests. Landing.