meta: add Heartbeat configuration

[SandyXSD]

Old sessions can only be cleaned up by old clients.

[codecov-commenter]

Codecov Report

Merging #1591 (ea396e7) into main (f78f922) will increase coverage by 0.03%.
The diff coverage is 86.53%.

❗ Current head ea396e7 differs from pull request most recent head da58d30. Consider uploading reports for the commit da58d30 to get more accurate results

@@            Coverage Diff             @@
##             main    #1591      +/-   ##
==========================================
+ Coverage   61.33%   61.36%   +0.03%     
==========================================
  Files         133      133              
  Lines       22424    22439      +15     
==========================================
+ Hits        13753    13770      +17     
+ Misses       7113     7099      -14     
- Partials     1558     1570      +12     

Impacted Files	Coverage Δ
pkg/meta/config.go	54.66% <ø> (ø)
pkg/meta/interface.go	55.83% <ø> (ø)
pkg/meta/utils.go	73.17% <ø> (ø)
pkg/meta/sql.go	67.65% <70.58%> (+0.51%)	⬆️
pkg/meta/base.go	72.24% <85.71%> (+0.18%)	⬆️
pkg/meta/tkv.go	76.63% <90.00%> (+0.76%)	⬆️
cmd/flags.go	95.48% <100.00%> (+0.13%)	⬆️
cmd/mount.go	70.08% <100.00%> (+0.13%)	⬆️
pkg/meta/redis.go	73.05% <100.00%> (+0.28%)	⬆️
pkg/chunk/utils_unix.go	73.33% <0.00%> (-20.00%)	⬇️
... and 5 more

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