[IMP] {google_,microsoft_}calendar: utilize description method

[mrsr-odoo]

This commit does the following- -Makes _get_customer_description to return HTML data. -Replace the description field with _get_customer_description for google_calendar and microsoft_calendar syncs.

Task-3458669

[robodoo]

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[mrsr-odoo]

hello @tde-banana-odoo , Suggested changes are done Please have a look Thanks !!

[tde-banana-odoo]

@robodoo r+

[robodoo]

@mrsr-odoo @tde-banana-odoo linked pull request(s) odoo/enterprise#47471 not ready. Linked PRs are not staged until all of them are ready.

[tde-banana-odoo]

@robodoo r+

[awa-odoo]

@robodoo r+

[robodoo]

@mrsr-odoo @awa-odoo linked pull request(s) odoo/upgrade#5850 not ready. Linked PRs are not staged until all of them are ready.