Fix accounts isSmartContract filtering

[stefangutica]

Reasoning

• smart contract accounts are filtered by currentOwner field on indexer, which is not always present on a smart contract address

Proposed Changes

• use prefix filtering insted of currentOwner field on indexer

How to test

• an address like erd1qqqqqqqqqqqqqpgqg726qlw8xqtcndmu2g0m8a2veundvpe8usys6l5law without currentOwner field on indexer, should be returned when fetching /accounts?isSmartContract=true&size=1000 , all SCs count being < 9500

[github-actions]

k6 load testing comparison.
Base Commit Hash: 496e7e9
Target Commit Hash: 25cc0e4

Metric	Base				Target				Diff
	Avg	Max	90	95	Avg	Max	90	95	Avg	Max	90	95
Mex	62.30	4744.02	157.42	193.72	57.69	1572.00	99.69	211.28	-7.40% ✅	-66.86% ✅	-36.67% ✅	+9.06% 🔴
Tokens	113.85	4962.73	207.05	240.90	93.61	1484.74	122.43	136.29	-17.78% ✅	-70.08% ✅	-40.87% ✅	-43.42% ✅
Blocks	90.62	4369.72	214.90	269.97	73.08	1911.14	158.49	269.92	-19.36% ✅	-56.26% ✅	-26.25% ✅	-0.02% ✅
Transactions	414.13	41446.33	228.99	258.40	336.45	34647.33	87.80	107.75	-18.76% ✅	-16.40% ✅	-61.66% ✅	-58.30% ✅
Accounts	63.86	4610.45	167.64	207.95	59.46	1861.64	105.25	211.51	-6.88% ✅	-59.62% ✅	-37.22% ✅	+1.71% 🔴
Pool	61.45	2971.06	161.59	195.07	58.31	1931.46	102.00	211.41	-5.11% ✅	-34.99% ✅	-36.87% ✅	+8.38% 🔴
Nodes	2855.41	27988.79	17123.81	27987.32	521.02	17672.90	149.49	170.67	-81.75% ✅	-36.86% ✅	-99.13% ✅	-99.39% ✅
Test Run Duration	60002.27				60002.72

Legend: Avg - Average Response Time, Max - Maximum Response Time, 90 - 90th Percentile, 95 - 95th Percentile
All times are in milliseconds.