Reword the dropdown limit paragraph

Reworded the paragraph to be more clear and
include a link to the related issue.

Also refactored how we are setting the project
IDs param.

doc/user/group/repositories_analytics/index.md

@@ -20,7 +20,7 @@ To get a CSV of the code coverage data for all of the projects in your group, go
 
 ![Code Coverage Modal](../img/group_code_coverage_csv_v13_4.png)
 
-Due to limitations in the API, in this first iteration the projects dropdown will only show up to 100 projects from your group. This will be updated in future releases to allow for selecting any project in your group. For now, selecting "All projects" will still download the report for all the projects in your group and not just the first 100.
+The projects dropdown shows up to 100 projects from your group. If the project you want to check is not in the dropdown list, you can select **All projects** to download the report for all projects in your group, including any projects that are not listed. There is a plan to improve this behavior in this [related issue](https://gitlab.com/gitlab-org/gitlab/-/issues/250684).
 
 For each day that a coverage report was generated by a job in a project's pipeline, there will be a row in the CSV which includes:
 

ee/app/assets/javascripts/analytics/repository_analytics/components/group_repository_analytics.vue

@@ -75,12 +75,11 @@ export default {
       const queryParams = new URLSearchParams({
         start_date: startDate,
         end_date: endDate,
-        project_ids: this.selectedProjectIdsParam,
       });
 
-      if (this.selectAllProjects) {
       // not including a project_ids param is the same as selecting all the projects
-        queryParams.delete('project_ids');
+      if (!this.selectAllProjects) {
+        queryParams.set('project_ids', this.selectedProjectIdsParam);
       }
 
       return `${this.groupAnalyticsCoverageReportsPath}&${queryParams.toString()}`;