fix config save - image optimization #476

[dpotkoc]

This closes #476

Previously on every config save, image optimization snippet was updated by Magento.

I implemented logic:
only if config option "Automatic Compression" was changed then Magento will update snippet.

Method for updating image snippet is getting value from this config option "Automatic Compression":

fastly-magento2/Observer/ConfigurationSave.php

Line 121 in cdf380c

$this->automaticCompressionHelper->updateVclSnippet($automaticCompression);

There is no point to update this vcl snippet in other cases.

Tested on Magento 2.4.2-p2 and 2.3.6-p1.

[vvuksan]

Released as 1.2.165