boss bar doesn't update its name until reloaded

Verification builds: 1.16.20.50 Release build, 1.13.31 Publish build

Summary: When changing the name of a boss bar in the "minecraft:boss" component, the name doesn't change until the bar is reloaded by the player.

Impact: Even though it's a small bug, it can be very confusing for players who change the model (and name) of a mech entity in the "World of Mechs" map.

Reproduction steps:

1. create a world and add the Behavior Pack attached to this report
2. summon/spawn an armor_stand
3. notice the name displayed by the boss bar is "Bar 1"
4. right click the armor_stand
5. notice the name displayed by the boss bar is still "Bar 1"
6. get away from the armor_stand until the boss bar isn't displayed anymore
7. go back to the armor_stand and notice the boss bar now displays the correct name: "Bar 2"

Expected result

The boss bar displays "Bar 2" as soon as the player right-clicks the armor_stand.

Actual result

The boss bar doesn't display "Bar 2" until the bar is reloaded.