fix: store heartbeat use redis setex with wrong timeunit

[AYue-94]

fix #1610

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 4 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...ackend/dao/redis/RedisStandAloneOperationImpl.java	0.00%	2 Missing ⚠️
.../io/sermant/backend/dao/redis/RedisClientImpl.java	0.00%	1 Missing ⚠️
...t/backend/dao/redis/RedisClusterOperationImpl.java	0.00%	1 Missing ⚠️

Flag	Coverage Δ	Complexity Δ
unittests	42.84% <0.00%> (+<0.01%)	182.00 <0.00> (ø)

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Files with missing lines	Coverage Δ	Complexity Δ
.../io/sermant/backend/dao/redis/RedisClientImpl.java	0.00% <0.00%> (ø)	0.00 <0.00> (ø)
...t/backend/dao/redis/RedisClusterOperationImpl.java	0.00% <0.00%> (ø)	0.00 <0.00> (ø)
...ackend/dao/redis/RedisStandAloneOperationImpl.java	0.00% <0.00%> (ø)	0.00 <0.00> (ø)

... and 1 file with indirect coverage changes