fix: NewRESTAddress use http as default scheme

[judehung]

fixes #990

The PR #986 set the scheme configurable in NewRESTAddress, but didn't consider a default value when scheme is empty string.

This commit will set http as the default value when scheme is an empty string.

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[codecov-commenter]

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Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 42.93%. Comparing base (b20d5f4) to head (f54e88f).

Files with missing lines	Patch %	Lines
dtos/address.go	0.00%	2 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #991      +/-   ##
==========================================
- Coverage   42.95%   42.93%   -0.02%     
==========================================
  Files         119      119              
  Lines        7206     7208       +2     
==========================================
  Hits         3095     3095              
- Misses       3768     3770       +2     
  Partials      343      343              

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[cloudxxx8]

LGTM