test_in_tail: relax too-tight timeouts in file-appended-after-start tests (#5446)

**Which issue(s) this PR fixes**:
Fixes #

**What this PR does / why we need it**:

`test_emit_with_read_lines_limit[flat 1]` fails intermittently on CI
(Ruby 3.4, windows-11-arm) with:

```
3) Failure: test_emit_with_read_lines_limit[flat 1](TailInputTest::singleline)
C:/a/fluentd/fluentd/test/plugin/test_in_tail.rb:509:in 'TailInputTest::TEST_VGFpbElucHV0VGVzdDo6c2luZ2xlbGluZQ#test_emit_with_read_lines_limit'
     506:       end
     507:
     508:       events = d.events
  => 509:       assert_equal(true, events.length > 0)
     510:       assert_equal({"message" => msg}, events[0][2])
     511:       assert_equal({"message" => msg}, events[1][2])
     512:       assert num_events <= d.emit_count
<true> expected but was
<false>

diff:
? tru e
? fals
? ???
Error: <true> expected but was
<false>.
```

https://github.com/fluent/fluentd/actions/runs/29549033055/job/87787458652#step:6:5460

i.e. no event was emitted within the 2s timeout.

These tests create/append the target file *after* `d.run` starts, so the
new content is only picked up by the periodic `refresh_watchers` timer.
The first emit is therefore structurally pinned to ~1s regardless of
machine speed, and `timeout: 2` leaves only ~1s of margin.

A timeout threshold sweep (30 runs each) shows both macOS and Windows 11
ARM share the ~1s floor (0.8s always fails), but Windows has large
jitter around it (13/30 fail at timeout 1.0s vs 0/30 on macOS). On the
slower, more-contended windows-11-arm CI runner that jitter occasionally
exceeds the 2s timeout, causing the flake.

`expect_emits:` returns as soon as the expected emits arrive (~1s), so
raising the timeout does not slow the passing case; a real "no emit"
regression is still caught, just after 10s instead of 2s.

Relax the timeouts of the three in_tail tests that share this "file
activity after run starts + short timeout" shape:

- test_emit_with_read_lines_limit: 2 -> 10
- test_always_read_from_head_on_detecting_a_new_file: 3 -> 10
- test_watch_wildcard_path_without_watch_timer: 1 -> 10 (Linux-only, but
had the tightest timeout)

**Docs Changes**:
N/A

**Release Note**:
N/A

Signed-off-by: Shizuo Fujita <fujita@clear-code.com>
Signed-off-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: Watson1978

test/plugin/test_in_tail.rb

@@ -498,7 +498,7 @@ def test_emit_with_read_lines_limit(data)
       d = create_driver(config)
       msg = 'test' * 2000 # in_tail reads 8192 bytes at once.
 
-      d.run(expect_emits: num_events, timeout: 2) do
+      d.run(expect_emits: num_events, timeout: 10) do
         Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt", "ab") {|f|
           f.puts msg
           f.puts msg
@@ -784,7 +784,7 @@ def test_watch_wildcard_path_without_watch_timer
 
       d = create_driver(config, false)
 
-      d.run(expect_emits: 1, timeout: 1) do
+      d.run(expect_emits: 1, timeout: 10) do
         Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt", "ab") {|f|
           f.puts "test3"
           f.puts "test4"
@@ -826,7 +826,7 @@ def test_emit_with_disable_stat_watcher(data)
     def test_always_read_from_head_on_detecting_a_new_file
       d = create_driver(SINGLE_LINE_CONFIG)
 
-      d.run(expect_emits: 1, timeout: 3) do
+      d.run(expect_emits: 1, timeout: 10) do
         Fluent::FileWrapper.open("#{@tmp_dir}/tail.txt", "wb") {|f|
           f.puts "test1\ntest2\n"
         }