Fix Build: Use default() to init custom hash based datastructures

[Shubham8287]

Description of Changes

hashbrown updated their default hasher - https://github.com/rust-lang/hashbrown/blob/master/CHANGELOG.md#v0150---2024-10-01.
Which is conflicting with DefaultHashBuilder in our custom types.

start initialising using ::default() to fix this.

API and ABI breaking changes

N/A

Expected complexity level and risk

1

Testing

Successful compiling should be enough.

• Write a test you've completed here.
• Write a test you want a reviewer to do here, so they can check it off when they're satisfied.