Updates of tensorflow-to-larod* examples

[pataxis]

• Use new model download
• Add a function test for tensorflow-to-larod example
• Add option to set custom environment image tag
• Align updates to tensorflow-to-larod-a8 example

Reference: ACAPSDK-1030

Checklist before requesting a review

• [x] I have performed a self-review of my own code
• [x] I have verified that the code builds perfectly fine on my local system
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] I have commented my code, particularly in hard-to-understand areas
• [x] I have verified that my code follows the style already available in the repository
• [x] I have made corresponding changes to the documentation