Preventing requests to the AnalyticsURL if it is not set

:bookmark_tabs: Summary

I noticed that my self-hosted Mermaid Live Editor is sending requests to the analytics URL when I didn't set the analytics URL and the mermaid domain, and I believe it should be configured according to the instructions provided in the https://github.com/mermaid-js/mermaid-live-editor?tab=readme-ov-file#to-configure-analytics.

My expectation is that the Mermaid Live Editor should not be sending requests to the analytics URL because, according to the README, the default setting is empty, which disables analytics.

Therefore, I would like to make changes to address this issue.

Brief description about the content of your PR:

Default env value is empty.
Prevent to request to mermaid.live for analytics if analyticsURL is not set.
analytics information is better to be empty because of default behavior at README

Resolves #

:straight_ruler: Design Decisions

Describe the way your implementation works or what design decisions you made if applicable:

:clipboard: Tasks

Make sure you

[x] :book: have read the contribution guidelines
[x] :computer: have added unit/e2e tests (if appropriate)
[x] :bookmark: targeted develop branch

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mermaid-js / mermaid-live-editor