fix: response for slash in website index document

[swarmHaseeb]

Checklist

• [x] I have read the coding guide
• [x] I have added tests to cover my changes.
• [x] I have filled out the description and linked the related issues

Description

Please refer to tagged issue for details. This pr sends correct response if there is a slash in website index document

Motivation and context (Optional)

Related Issue (Optional)

This pr fixes #2661

Screenshots (if appropriate):

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This change is 

[aloknerurkar]

Not sure if this is correct. We can have / in the index document. The way it works is for each folder you can configure the index document.

So you can have 2 index files: index.html someFolder/index.html

I guess this is why the tests are failing.