[flutter_tool] Allow analytics without a terminal attached

[zanderso]

Description

The Flutter tool may be wrapped in a shell script, for example, in which case we'd still like to collect analytics.

Tests

The relevant test was updated.

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.

[jonahwilliams]

LGTM

[codecov]

Codecov Report

Merging #36208 into master will decrease coverage by 0.01%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##           master   #36208      +/-   ##
==========================================
- Coverage   55.03%   55.01%   -0.02%     
==========================================
  Files         187      187              
  Lines       17241    17242       +1     
==========================================
- Hits         9488     9486       -2     
- Misses       7753     7756       +3

Flag	Coverage Δ
#flutter_tool	55.01% <66.66%> (-0.02%)	⬇️

Impacted Files	Coverage Δ
packages/flutter_tools/lib/src/usage.dart	75.55% <ø> (ø)	⬆️
.../flutter_tools/lib/src/runner/flutter_command.dart	82.66% <100%> (+0.07%)	⬆️
packages/flutter_tools/lib/src/base/utils.dart	94.47% <50%> (-0.51%)	⬇️
...lutter_tools/lib/src/build_system/targets/ios.dart	0% <0%> (-100%)	⬇️
...tter_tools/lib/src/build_system/targets/macos.dart	64.7% <0%> (-11.77%)	⬇️
...utter_tools/lib/src/build_system/targets/dart.dart	83.33% <0%> (-1.29%)	⬇️
packages/flutter_tools/lib/src/version.dart	96.05% <0%> (-0.99%)	⬇️
packages/flutter_tools/lib/src/build_info.dart	69.06% <0%> (-0.56%)	⬇️
.../flutter_tools/lib/src/fuchsia/fuchsia_device.dart	55.76% <0%> (+0.37%)	⬆️
packages/flutter_tools/lib/src/vmservice.dart	39.61% <0%> (+0.47%)	⬆️
... and 2 more

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