[receiver/filelogreceiver] Filelogreceiver doesn't read from file in case there are two or more empty lines at the beginning

[perk]

Describe the bug
Filelogreceiver doesn't read from file in case there are two or more empty lines at the beginning when the start_at: beginning is used.

Steps to reproduce
Create the following logs.txt file to read the data from:

three
four
five

Apply the following configuration:

receivers:
  filelog:
    include:
    - ./logs.txt
    start_at: beginning

exporters:
  logging:

service:
  pipelines:
    logs:
      receivers: [filelog]
      exporters: [logging]

Run the otelcol:

./otelcol-contrib --config config.yaml

See the following lines:

2022-05-18T14:16:59.785+0200	info	service/collector.go:146	Everything is ready. Begin running and processing data.
2022-05-18T14:16:59.988+0200	info	file/file.go:174	Started watching file	{"kind": "receiver", "name": "filelog", "operator_id": "file_input", "operator_type": "file_input", "path": "logs.txt"}

Try to add anything into the file:

echo six >> logs.txt
echo seven >> logs.txt

Nothing happens at this point, file is not being read.

What did you expect to see?
I'd expect to see all the logs - old a new ones - collected.

What did you see instead?
Collector doesn't receive the data from the file at all.

What version did you use?
0.51.0

What config did you use?

receivers:
  filelog:
    include:
    - ./logs.txt
    start_at: beginning

exporters:
  logging:

service:
  pipelines:
    logs:
      receivers: [filelog]
      exporters: [logging]

Environment
OS: Ubuntu 20.04, MacOS 12.3.1

[djaglowski]

Related to #10125 and #10127

[dmitryax]

@djaglowski please assign accordingly if we have someone to work on this