[exporter/clickhouse] Fix incorrect ServiceName set for Logs Records (o…

…pen-telemetry#36350)

#### Description
Fixing a bug in `clickhouseexporter` when ServiceName field in
ClickHouse for `otel_logs` table is set from previous Log Record, when
current LogRecord doesn't have `service.name` set

#### Link to tracking issue
Fixes open-telemetry#36349

#### Testing
Respective unit test is added to code

---------

Co-authored-by: Christos Markou <[email protected]>
Co-authored-by: Alex Boten <[email protected]>

.chloggen/fix_clickhouse-exporter-log-service-name.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: clickhouseexporter
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Fix incorrect Resource Attribute `service.name` translation to ClickHouse ServiceName field for Logs Records
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [36349]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []