Suggests to use a JSON structured log instead

Related to https://gitlab.com/gitlab-org/gitlab-ce/issues/54102

This allows us to set the encoding of an IO passed without reading it
into memory.

This is useful if we want to stream files into Gitaly. Like we do when
uploading a new file to the repository.

Saved Wiki content goes through the GitalyClient::WikiService, which calls
StringIO#set_encoding on the input stream. The problem is that this call
mutates the encoding of the given string object to ASCII-88BIT, which
causes problems for models expecting the data to still be in UTF-8.

Freezing the input disables this behavior:
https://github.com/ruby/ruby/blob/v2_4_4/ext/stringio/stringio.c#L1583

Closes #50590

Closes gitaly#1101

Fixes gitlab-development-kit#321

They're costly. This will also avoid some edge cases where
charlock_holmes assigns a weird encoding to a perfectly valid UTF-8
string.

They're costly. This will also avoid some edge cases where
charlock_holmes assigns a weird encoding to a perfectly valid UTF-8
string.

remove some lint

It is recommended that we set this to 50:
https://gitlab.com/gitlab-org/gitlab-ce/issues/35098#note_35036746

In this particular issue, the confidence was 42 for Shift JIS,
but in fact that's encoded in UTF-8 just with a single bad
character. In this case, we shouldn't try to treat it as Shift JIS,
but just treat it as UTF-8 and remove invalid bytes.

Treating it like Shift JIS would corrupt the whole data.

Unfortunately, the diff which would cause this could not be
disclosed therefore we can't use it as a test example.