Truncated PR comments don't have a header
### System information
- **OS Platform and Distribution (e.g., Linux Ubuntu 16.04)**:

Ubuntu 16.04

- **Modin version** (`modin.__version__`):

0.7.3+78.g2d74813

- **Python version**:

Python 3.7.7

- **Code we can use to reproduce**:

<!--
You can obtain the Modin version with

python -c "import modin; print(modin.__version__)"
-->

### Describe the problem
<!-- Describe the problem clearly here. -->

When comment is too long, usually because of failed tests, comment script cuts off its beginning which contains `<details>` and `<summary>` tags. This makes comment text very long inside of PR.

### Source code / logs
<!-- Include any logs or source code that would be helpful to diagnose the problem. If including tracebacks, please include the full traceback. Large logs and files should be attached. Try to provide a reproducible test case that is the bare minimum necessary to generate the problem. -->

diff --git a/ci/teamcity/comment_on_pr.py b/ci/teamcity/comment_on_pr.py
index ad4847c3a..b21ea04f3 100644
--- a/ci/teamcity/comment_on_pr.py
+++ b/ci/teamcity/comment_on_pr.py
@@ -40,8 +40,6 @@ split_by_first = (
 split_by_second = "--------------------------------------------------------------------------------------"
 
 for out in pytest_outputs:
-    full_comment += "<details><summary>Tests Logs</summary>\\n"
-    full_comment += "\\n\\n```\\n"
     content = open(out, "r").read()
     full_comment += "".join(
         "".join(
@@ -54,6 +52,7 @@ for out in pytest_outputs:
     )
     if len(full_comment) > 65_000:
         full_comment = full_comment[-65_000:] + "\\n\\n<b>Remaining output truncated<b>\\n\\n"
+    full_comment = "<details><summary>Tests Logs</summary>\\n\\n\\n```\\n" + full_comment
     full_comment += "\\n```\\n\\n</details>\\n"
 if "FAILURES" not in full_comment:
     header += '<h3 align="center">Tests PASSed</h3>\\n\\n'
['ci/teamcity/comment_on_pr.py']