KAFKA-9479: Print describe --state header once for multiple groups

[Hana1025]

When describing multiple consumer groups with --state (including
--all-groups), compute column widths across all groups and print the
header once.

[smjn]

@Hana1025
Pease provide sample output before and after with no groups, single group and multiple groups.

[Hana1025]

@Hana1025 Pease provide sample output before and after with no groups, single group and multiple groups.

@smjn Thanks for the review. Sample output for kafka-consumer-groups.sh --describe --state is below (using --bootstrap-server localhost:9092).

No consumer groups (--all-groups on a cluster with no groups)
Before / After: (no table output)

printStates returns immediately when there are no printable groups.

Single group (--group group1 --state)
Before / After: (unchanged — one header and one data row)

GROUP COORDINATOR (ID) ASSIGNMENT-STRATEGY STATE #MEMBERS
group1 localhost:9092 (1) range Stable 1
Multiple groups (--all-groups with group1 and group2)
Before: header repeated for each group

GROUP COORDINATOR (ID) ASSIGNMENT-STRATEGY STATE #MEMBERS
group1 localhost:9092 (1) range Stable 1
GROUP COORDINATOR (ID) ASSIGNMENT-STRATEGY STATE #MEMBERS
group2 localhost:9092 (1) range Stable 1
After: header printed once; column widths computed across all groups

GROUP COORDINATOR (ID) ASSIGNMENT-STRATEGY STATE #MEMBERS
group1 localhost:9092 (1) range Stable 1
group2 localhost:9092 (1) range Stable 1
The same behavior applies when multiple groups are specified with repeated --group flags (e.g. --group group1 --group group2 --state).

Also pushed commit b7db1be with a regression test that asserts the state header is printed only once for multiple --group --state.

[ghost]

A label of 'needs-attention' was automatically added to this PR in order to raise the
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