Revert "[chromebox_for_meetings] Combine logs with newlines"

This reverts commit 564edbfd2628ecb2fa16dca9729edccf74937c1f.

Reason for revert: Causing related consistent test failures:

HotlogLogSourceTest.RequestVaryingAmountOfLogLines
HotlogLogSourceTest.TestBatchSizeCorrectlyLimitsOutput
HotlogLogSourceTest.TestCrashRecovery
HotlogLogSourceTest.VerifyNewLinesAppearAfterRefresh
HotlogLogSourceTest.VerifyNewLinesAppearAfterRotation

See
https://ci.chromium.org/ui/p/chromium/builders/ci/linux-cfm-rel/57480/blamelist

Original change's description:
> [chromebox_for_meetings] Combine logs with newlines
>
> Log lines that contain newlines should be treated as
> a single log, so make sure to concatenate them with
> newlines if they appear.
>
> Bug: b:341296654
> Change-Id: Ib96078318c968ee62a09fc53fbf47fc81185833a
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5545929
> Commit-Queue: Niko Tsirakis <ntsirakis@google.com>
> Reviewed-by: Jenny Zhang <jennyz@chromium.org>
> Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1303749}

Bug: b:341296654
Change-Id: I92b547b2b0e791b235d5e4f8829445f23aa0542b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5553312
Owners-Override: Katie Dektar <katie@chromium.org>
Commit-Queue: Katie Dektar <katie@chromium.org>
Auto-Submit: Katie Dektar <katie@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1303911}