[SERVICES-1902] fix token derived EGLD price

[claudiulataretu]

Reasoning

• for a specific token there are two ways: paired directly with EGLD or paired with another token
• tokens that are paired with EGLD and with other tokens which don't have a pair with other token can't get the derived EGLD price

Proposed Changes

• for a specific token it will filter out those pairs that the paired token doesn’t have a pair with other tokens

How to test

query Tokens {
	tokens {
		identifier
		decimals
		price
                derivedEGLD
		type
	}
}

• query should return price for all tokens

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (42cedea) 56.14% compared to head (e01d7b4) 56.21%.

Additional details and impacted files

@@               Coverage Diff               @@
##           development    #1216      +/-   ##
===============================================
+ Coverage        56.14%   56.21%   +0.06%     
===============================================
  Files              235      235              
  Lines             7826     7838      +12     
  Branches           519      519              
===============================================
+ Hits              4394     4406      +12     
+ Misses            2990     2989       -1     
- Partials           442      443       +1     

Flag	Coverage Δ
unittests	56.21% <92.30%> (+0.06%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
src/modules/pair/mocks/pair.constants.ts	70.27% <100.00%> (+8.20%)	⬆️
...c/modules/tokens/services/token.compute.service.ts	81.25% <80.00%> (+9.58%)	⬆️

... and 2 files with indirect coverage changes

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