awslogs: replace channel-based mocks

[samuelkarp]

- What I did
awslogs: replace channel-based mocks

(related to #42690)

- How I did it
Rewrote the mock so tests define mock functions rather than specifying inputs and outputs via channels. This reduces the overall number and use of channels in the unit tests.

- How to verify it

GO111MODULE=off go test ./daemon/logger/awslogs

- Description for the changelog
N/A

[thaJeztah]

Failure on win-2022/c8d is a known flaky; TestNetworkDBIslands #42459

Failure on win-2022 is unrelated, but seeing a lot of these recently, so leaving a comment here, in case it's specific tests that are more prone failing on this;

=== FAIL: github.com/docker/docker/integration-cli TestDockerSuite/TestInspectTemplateError (4.17s)
    check_test.go:170: assertion failed: error is not nil: Error response from daemon: container 85461ca939f9b77170803c9831a3298c4331af4625e7c6fa399410a5c7804f7f: driver "windowsfilter" failed to remove root filesystem: failed to detach VHD: failed to detach virtual disk: The device is not ready.: rename D:\CI\PR-43139\1\daemon\windowsfilter\85461ca939f9b77170803c9831a3298c4331af4625e7c6fa399410a5c7804f7f D:\CI\PR-43139\1\daemon\windowsfilter\85461ca939f9b77170803c9831a3298c4331af4625e7c6fa399410a5c7804f7f-removing: Access is denied.: failed to remove 85461ca939f9b77170803c9831a3298c4331af4625e7c6fa399410a5c7804f7f
    --- FAIL: TestDockerSuite/TestInspectTemplateError (4.17s)

[thaJeztah]

LGTM

[thaJeztah]

windows failures are unrelated