Upgrade to Lucene-7.4-snapshot-6705632810 (#30519)

This snapshot is to include LUCENE-8298 which allows DocValues updates
to reset a value. This is needed for the Lucene rollback work.

Author: dnhatn

buildSrc/version.properties

@@ -1,5 +1,5 @@
 elasticsearch     = 6.4.0
-lucene            = 7.4.0-snapshot-1ed95c097b
+lucene            = 7.4.0-snapshot-6705632810
 
 # optional dependencies
 spatial4j         = 0.7

modules/lang-expression/licenses/lucene-expressions-7.4.0-snapshot-1ed95c097b.jar.sha1

@@ -0,0 +1 @@
+f72ad4b6474c2d59b0eed0ca84eddd1f99d29129

modules/lang-expression/licenses/lucene-expressions-7.4.0-snapshot-6705632810.jar.sha1

@@ -0,0 +1 @@
+b4e19c53f29fa9b40bd7ad12ff598e3f08d507a3

plugins/analysis-icu/licenses/lucene-analyzers-icu-7.4.0-snapshot-1ed95c097b.jar.sha1

@@ -0,0 +1 @@
+23dd8cb3834f3641d9b3e8bc3d38281389a597bc

plugins/analysis-icu/licenses/lucene-analyzers-icu-7.4.0-snapshot-6705632810.jar.sha1

@@ -0,0 +1 @@
+e8119a17448a6f5512ded0bd2a6faa7fc8e70890